Nuclear Weapons


Nuclear Weapons


A nuclear weapon is an explosive device that releases enormous amounts of energy, in the form of blast wave, heat radiation, and radioactive fallout, through either an uncontrolled nuclear fission chain reaction or combined nuclear fission and fusion reactions that result in a powerful explosion.

In nuclear fission (or splitting), the nucleus of an atom splits into two or more subatomic particles (neutrons and protons) which produce additional fissions. In this process, large amounts of energy and highly radioactive particles are released. Nuclear weapons based on fission are called atomic bombs or A-bombs. The first generation of nuclear weapons was the A-bomb. The nuclear fuel used in A-bombs is highly enriched uranium – U-235 uranium enriched to 90 per cent or more – or weapons grade plutonium (Pu 239). Approximately 52 kilograms of uranium 235 or 16 kilograms of plutonium 239 is the minimum amount of fissile material – the so-called “critical mass” – that is needed to achieve and maintain the fission chain reaction in a nuclear weapon.

Nuclear fusion is the fusing of two or more lighter atoms into a larger one. Nuclear weapons that use a combination of a primary nuclear fission reaction to compress and ignite a secondary nuclear fusion reaction to provide explosive power are called hydrogen bombs, H-bombs, or thermonuclear bombs.

The world’s first atomic bomb was detonated at a nuclear test site in New Mexico by the United States in July 1945. On 6 August 1945, the first atomic bomb was used in war on the Japanese city of Hiroshima. The bomb had a yield of 13.6 kilotons – each kiloton equal to the explosive force of nearly one thousand tons of TNT. Three days later, the US dropped a second nuclear bomb, with a yield of 18 kilotons, on Nagasaki. The bombings resulted in the deaths of approximately 200,000 people, mainly civilians, from acute injuries sustained from the explosions. Since then nuclear weapons have not been used as military weapons, but only as a political and military deterrent.

The second generation of nuclear weapons – hydrogen bombs – was developed in 1952 and was tested for the first time in November 1952, on one of the Marshall Islands, by the United States, with a yield of 10.6 megatons – each megaton equal to the explosive force of over 900,000 tons of TNT. The Soviet Union tested its first H-bomb in August 1953. A thermonuclear bomb can be many thousands of times more powerful than pure fission atomic bombs. Today the principal part of the nuclear arsenals of the United States and Russia consists of thermonuclear bombs. China, France, and the United Kingdom also have such nuclear weapons.

In this book, the term “nuclear weapons” includes both atomic bombs and hydrogen bombs.


According to the latest estimates from the Stockholm International Peace Research Institute (SIPRI), as of January 2015 there was an estimated total of approximately 15,850 nuclear weapons in the world. Deployed warheads and stocks of nuclear weapons in each of the five nuclear-weapon states and the four nuclear-armed states1 are estimated as follows:


* “Deployed warheads” include operational warheads installed on missiles or located on bases with operational forces, i.e., ready for use on short notice.

† “Other warheads” include nuclear weapons in reserve, awaiting dismantlement or requiring preparation (e.g., assembly or loading on launchers) before they become fully operational.

Source: SIPRI Yearbook 2015.

Of the total number of nuclear weapons, the United States and Russia maintain 14,760 (93 per cent of the total number) in their arsenals.

The number of nuclear weapons deployed by the United States includes – in addition to approximately 1,900 strategic warheads2 – about 180 non-strategic (tactical) nuclear weapons, deployed in Europe. Other warheads in the US nuclear arsenal include about 2,680 warheads held in reserve and 2,500 retired warheads awaiting dismantlement. It is estimated that the United States has a total of 500 tactical nuclear warheads, which are included in the above numbers.

It is estimated that Russia maintains a nuclear arsenal of approximately 4,380 nuclear warheads assigned to operational forces, of which 2,430 are strategic warheads. About 1,780 of the strategic warheads are deployed on ballistic missiles (more than half of the warheads are deployed on some 300 land-based ballistic missiles and approximately 400 warheads on 140 SLBMS (submarine-launched ballistic missiles)). Sixty warheads are deployed with 60 bomber aircraft. Nearly 700 bomber and submarine warheads are kept in storage. Russia also has approximately 2,000 tactical nuclear weapons – all kept in storage. There are 3,120 warheads that are retired or awaiting dismantlement.

All of Britain’s 215 nuclear weapons are sea-based Trident SLBM and their associated warheads. The United Kingdom has four nuclear-powered ballistic missile submarines.

France’s nuclear weapons consist of 300 warheads for 48 SLBM and 54 air-launched cruise missiles. France also has four nuclear-powered ballistic missile submarines.

China’s nuclear warheads are believed to be kept in storage, not ready for immediate launch. An estimated 190 warheads are assigned to land-based ballistic missiles and aircraft.

Compared with January 2014, the total number of nuclear weapons in the world decreased by approximately 500 warheads. The total number of weapons decreased from January 2012 to January 2013 by 1,730 weapons and by about 950 from January 2013 to January 2014. The United States and Russia reduced their nuclear weapons from 2014–15 by 40 and 500 warheads, respectively, as a result of the Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms (“New START”) and unilateral reductions. The United Kingdom reduced its nuclear weapons by ten nuclear warheads. China increased its arsenal by ten warheads. In France and in the nuclear-armed states, the numbers of nuclear warheads remained unchanged. However, all the nuclear-weapon states and nuclear-armed states are modernizing their nuclear forces and have thus demonstrated that they are determined to retain sizeable nuclear arsenals for the foreseeable future. It is generally assumed that Israel became a de facto nuclear-weapon state as early as 1973. Israel has neither officially confirmed nor denied that it possesses nuclear weapons but is universally believed to possess them. There is no authoritative confirmation that North Korea has operational nuclear weapons, but according to SIPRI’s estimates, North Korea has produced sufficient quantities of plutonium to build six to eight nuclear weapons.

About thirty other countries are assumed to have the technological capacity to develop and produce nuclear weapons, Iran among them. It was estimated that Iran would have been able to test its first nuclear weapon within a few years – or perhaps earlier. This presumed Iranian ambition was brought to an end by the so-called Joint Comprehensive Plan of Action of 14 July 2015 on the future of Iran’s nuclear program. According to the Arms Control Association, the Plan of Action – the comprehensive nuclear agreement between Iran and the P5+1 – i.e., the five permanent members of the Security Council: China, France, Russia, the United Kingdom, and the United States, and Germany – verifiably blocks Iran’s pathways to nuclear weapons development and guards against a clandestine Iranian nuclear weapons program. When fully implemented, the agreement will be a net plus for non-proliferation and will enhance US and regional security.3

Iraq’s efforts to obtain nuclear weapons capability were temporarily shut down by Israel’s bombing of Iraq’s nuclear facilities in 1981 and were completely phased out after the First Gulf War in 1991. In 2007, Israel bombed Syria’s nuclear installations and thus brought Syria’s attempts to develop nuclear weapons to an end.

South Africa is the only country to have built nuclear weapons and then voluntarily dismantled them and abandoned its nuclear weapons program. South Africa had pursued a nuclear weapons program from 1974 through 1990 as a deterrent to counter a perceived Soviet threat in the region. In the 1980s, South Africa built six nuclear weapons and had started building a seventh. Less than a decade after assembling its first nuclear weapon, South Africa voluntarily joined the Treaty on Non-Proliferation of Nuclear Weapons (NPT) as a non-nuclear-weapon state, and allowed international inspections of its former nuclear weapons program.


The United States and the Soviet Union/Russia have signed a number of treaties with significant limitations on the numbers of their strategic nuclear weapons and their means of delivery: the SALT I and II (Interim Agreement and Treaty on Limitation of Strategic Offensive Arms), START I and II (Strategic Arms Reduction Treaties), and SORT (Treaty on Strategic Offensive Reductions) (see page 247). During the Cold War, when their arsenals were at their highest level, the two former superpowers possessed a total of an estimated 64,500 nuclear weapons in 1986. Since 1991, 80 per cent of the American and Russian nuclear weapons have been eliminated. The bilateral agreements have superseded each other and are therefore of mainly historical interest.

The most recent treaty between the United States and Russia on further reductions and limitations of their offensive strategic nuclear weapons is the Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms of 2010 (New START or Prague Treaty). The treaty entered into force on 5 February 2011 and will remain in force for ten years, until 5 February 2021, unless it is superseded earlier by a subsequent agreement on the reduction and limitation of strategic offensive arms. According to the treaty, each of the states must reduce the number of their deployed strategic ICBMS (intercontinental ballistic missiles), SLBMS, and heavy bombers to no more than 700 and the number of warheads on their deployed ICBMS, SLBMS, and heavy bombers to a maximum of 1,550 before 5 February 2018. The treaty replaces the previous agreements between the two countries on the reduction of nuclear weapons, the latest of which is the Treaty on Strategic Offensive Reductions of 2002 (SORT or Moscow Treaty), by which each state committed to reducing and limiting its strategic nuclear warheads, so that by 31 December 2012 the aggregate number of such warheads did not exceed 1,700 to 2,200 for each party.

In 1987, the United States and the Soviet Union concluded an important bilateral agreement on the elimination of their intermediate-range and shorter-range missiles: Treaty Between the United States of America and the Union of Soviet Socialist Republics on the Elimination of Their Intermediate-Range and Shorter-Range Missiles (INF). The treaty entered into force in 1988. The INF Treaty globally abolished an entire class of American and Soviet land-based intermediate-range and shorter-range missiles with ranges of between 500 and 5,500 kilometres, i.e., not only the missiles deployed in Europe, but all the missiles in the arsenals of the two countries in those ground-launched categories. As a result of the INF Treaty, a total of 859 US intermediate-range and shorter-range missiles (Pershing and ground-launched cruise missiles) and 1,752 Russian intermediate-range and shorter-range missiles (various types of SS-missiles) were dismantled and destroyed. The INF Treaty was a breakthrough for the control of nuclear weapons; the treaty was the first disarmament agreement that included a comprehensive regime for mutual on-site inspections, i.e., on the territories of both participating states.

Unfortunately, the INF Treaty has come under pressure from Russia, which is feeling increasingly limited by the treaty against the background of the Americans’ continued modernization of their nuclear arsenal and development of a ballistic missile defence system. The United States is accusing Russia of having technically violated the INF by testing a new type of intermediate-range cruise missile for use at sea. The missile was tested from a ground-based launcher, which is not allowed under the treaty. Russia has threatened to withdraw from the treaty as a response to US moves. The two parties should resolve this issue within the framework of the treaty, in the Special Verification Commission.


Most of the American and Russian strategic nuclear weapons are deployed in missile silos in their respective national territories and onboard US and Russian nuclear submarines that constantly patrol the world’s oceans.

However, American tactical nuclear weapons are still deployed in five European countries in northwestern and southeastern Europe, in Belgium, Germany, Italy, the Netherlands, and Turkey. This continued presence in Europe of US tactical nuclear bombs is a concern. Tactical (or non-strategic) nuclear weapons have a much lower yield and shorter range than strategic nuclear weapons and are designed for use on the battlefield. Although the number of US tactical nuclear weapons in Europe has been greatly reduced, from approximately 7,300 nuclear warheads in 1971, there are still today approximately 184 nuclear aircraft-delivered B61 gravity bombs deployed at six US bases in the above five European countries. The newly developed version, B61-12, which has increased accuracy in hitting targets and greater capability in penetratting hardened targets, is scheduled for deployment in Europe by 2020. The existing nuclear bombs in the European countries are not operationally deployed, but stored separately from their aircraft delivery systems in underground vaults in protected shelters. However, the risk of accidents while handling the bombs during training and maintenance exercises, sabotage by terrorist attacks against the nuclear weapons bases, or theft can never be completely ruled out. Because of their small size and mobility, tactical nuclear bombs are particularly vulnerable to theft or risk of an unauthorized launch.

It no longer makes sense to maintain this tactical nuclear deterrence capability in Western Europe more than twenty-five years after the end of the Cold War – even in light of the conflict in the Ukraine and the resulting serious increase in tensions between the US/NATO and Russia. The US tactical nuclear weapons had no deterrent effect on Russia’s decision to annex the Crimea and invade the eastern part of Ukraine. The deployment of tactical US nuclear weapons in Europe was originally motivated by the former massive Soviet predominance of conventional armed forces. With the dissolution of the Soviet Union in December 1991, the threat from Soviet conventional forces disappeared. Today, conventional NATO forces are technically superior to those of Russia. The tactical US nuclear weapons in Europe no longer have any real and additional military significance and deterrence effect beyond the one already provided by the American, British, and French nuclear arsenals – only a political and symbolic significance, as an expression of transatlantic American-European unity and of NATO’s common defence solidarity. The continued deployment and modernization of these weapons in Europe is very costly: It is estimated by the Congressional Budget Office at 7 billion dollars and by the Pentagon at 10 billion dollars over the next decade. Moreover, if the modernized B61-12s are deployed, Russia has threatened to deploy its tactical nuclear missiles in the Russian enclave of Kaliningrad in Eastern Europe. If the American tactical nuclear weapons were relocated from European bases to national storage facilities in the United States, the Russians would probably be more willing to initiate new talks with the US on possible further overall reductions of both American and Russian strategic nuclear weapons.

Proponents of maintaining the tactical US nuclear weapons in Europe, in particular the Central European NATO countries, such as Poland, the Czech Republic, and the Baltic states, argue that these weapons continue to have not only a symbolic meaning as an expression of defence solidarity but also demonstrate America’s determination to guarantee the security of Europe. In this context, proponents refer to the continued advantage in the numbers of Russian tactical nuclear weapons and the expected increasing role of nuclear weapons in Russia’s defence posture. Under the current circumstances in Ukraine and Russia’s involvement in the conflict, withdrawing American tactical nuclear weapons from Europe would send a wrong signal and be perceived in Moscow as an expression of weakness.

The current threats to the security of Europe are mainly coming from Middle Eastern countries or extremist religious groups in the Middle East, such as Islamic State (IS). These threats can only be countered effectively by building a missile defence for Europe in the southeastern part of the continent. In case of increasing threats and escalating conflict, there will be sufficient time to transfer tactical nuclear weapons to Europe from reserve stocks in the United States. Alternatively, a smaller number of tactical nuclear weapons could be maintained in Turkey and Italy. In addition, the strategic nuclear weapons (SLBM) deployed onboard American and British submarines constitute an overwhelming deterrence force, which – unlike the tactical US nuclear weapons deployed in the five European countries – are constantly operational and may be launched at short notice.

At the request of the former German foreign minister, Guido Westerwelle, there have been increasing calls since 2009 to reconsider the role of the American tactical nuclear weapons in Europe, in particular from Belgium, Germany, and the Netherlands, with support from Norway and Luxembourg. A decision to continue – for political reasons – to have tactical US nuclear weapons deployed in Europe is also becoming more relevant and urgent in light of concrete plans in Germany, Belgium, the Netherlands, Italy, and Denmark to replace their current fighter aircraft (F-16 and Tornado), some of which are currently equipped to carry nuclear bombs (“dual-capable aircraft”). The question is whether the new fighter aircraft (presumably the US-built F-35 JSF) in these countries should be equipped to carry nuclear bombs, which would add considerably to the costs of the aircraft.

It seems to be the general view among all the NATO member states that any decision to remove the tactical nuclear weapons from Europe should be based on consensus.

Legal Considerations

From the point of view of international law, the deployment of US tactical nuclear weapons on the territories of the five above-mentioned European non-nuclear-weapon states must be considered a violation of Articles 1 and 2 of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) – if not of the treaty’s letter – of its purpose and aim (see more about the NPT below). This is the case even though the United States has not transferred the nuclear weapons or the control over them to the host countries. Another consideration is that maintaining the presence of the tactical US nuclear weapons in Europe contradicts and undermines the stated aim of European countries to promote the disarmament of nuclear weapons. As long as US nuclear weapons are deployed in Europe, it is unrealistic to expect Russia to take steps to reduce its tactical nuclear weapons in Europe, i.e., in the western part of Russia. It would be in NATO’s interest for Russia to reduce its tactical weapons.

In NATO’s Strategic Concept, adopted at the NATO summit in Washington in April 1999, the tactical US nuclear weapons in Europe are given less importance than before. However, these weapons can only be reduced if Russia does the same. In this context it should be noted that the tactical US nuclear weapons previously deployed in Greece were withdrawn in 2001. In 1991, the US nuclear weapons in South Korea and Japan were also withdrawn from these countries. Why not remove this relic of the Cold War from Europe, which today – in spite of the Ukraine conflict – must be considered less of a potential conflict area than the Korean peninsula and Japan?


There are still a number of countries, including the member states of NATO that maintain a deterrence policy and strategy based on nuclear weapons. These countries also do not exclude the use of nuclear weapons in case they are attacked with conventional weapons. NATO’s nuclear policy is laid down in NATO’s “Strategic Concept for the Defence and Security of the Members of the North Atlantic Treaty Organization,” adopted by the heads of state and government at the NATO Summit in Lisbon in November 2010. According to the Strategic Concept’s paragraph 17, “Deterrence, based on an appropriate mix of nuclear and conventional capabilities, remains a core element of our overall strategy. The circumstances in which any use of nuclear weapons might have to be contemplated are extremely remote. As long as nuclear weapons exist, NATO will remain a nuclear alliance.” Paragraph 19 further states: “We will ensure that NATO has the full range of capabilities necessary to deter and defend against any threat to the safety and security of our populations. Therefore, we will maintain an appropriate mix of nuclear and conventional forces.” However, in paragraph 26, the Strategic Concept also expresses the Alliance’s readiness to create the conditions for a world without nuclear weapons: “We are resolved to seek a safer world for all and to create the conditions for a world without nuclear weapons in accordance with the goals of the Nuclear Non-Proliferation Treaty, in a way that promotes international stability, and is based on the principle of undiminished security for all. With the changes in the security environment since the end of the Cold War, we have dramatically reduced the number of nuclear weapons stationed in Europe and our reliance on nuclear weapons in NATO strategy. We will seek to create the conditions for further reductions in the future.” The main content of the Strategic Concept is repeated in Alliance’s “Deterrence and Defence Posture Review,” adopted at the Summit Meeting in Chicago in May 2012, which also contains the following text: “Nuclear weapons are a core component of NATO’s overall capabilities for deterrence and defence alongside conventional and missile defence forces . . . The circumstances in which any use of nuclear weapons might have to be contemplated are extremely remote. As long as nuclear weapons exist, NATO will remain a nuclear alliance.” The last statement is repeated again in the “Wales Summit Declaration” of 5 September 2014, which also states that “Deterrence, based on an appropriate mix of nuclear, conventional, and missile defence capabilities, remains a core element of our overall strategy.” The above statements confirm that NATO does not exclude the use of nuclear weapons.


The most important global agreement on nuclear weapons reduction is the “Treaty on the Non-Proliferation of Nuclear Weapons” (NPT) of 1 July 1968. The treaty, which came into force in March 1970, and is considered to be the cornerstone of international efforts to prevent the spread of nuclear weapons, now has 191 states parties, i.e., the entire world community except Israel, India, and Pakistan (plus the new state of South Sudan, which has not yet joined the treaty). At a review conference in May 1995 to review the functioning of the treaty, the states parties decided to extend it indefinitely.

North Korea was a party to the NPT but in March 1993 the country announced that it was withdrawing from the NPT. In January 2003, North Korea cancelled its participation in the NPT effective the following day, and then declared that it possessed nuclear weapons. However, because of procedural errors, the validity of North Korea’s withdrawal from the NPT was disputed. The withdrawal did not comply with the provisions of Article 10 on withdrawal and was therefore not recognized. It remains to be seen whether North Korea will continue its clandestine and controversial nuclear program in order to develop (more?) nuclear weapons and nuclear weapon delivery capabilities (missiles).

The NPT makes an important distinction between two categories of states: Nuclear-weapon states and non-nuclear-weapon states. The non-proliferation obligations for the nuclear-weapon states are laid down in Article 1 of the treaty: “Each nuclear-weapon state party to the Treaty undertakes not to transfer to any recipient whatsoever nuclear weapons or other nuclear explosive devices or control over such weapons or explosive devices directly, or indirectly; and not in any way to assist, encourage, or induce any non-nuclear-weapon state to manufacture or otherwise acquire nuclear weapons or other nuclear explosive devices, or control over such weapons or explosive devices.”

The nuclear-weapon states parties are defined in Article 9, paragraph 3: “For the purposes of this Treaty, a nuclear-weapon state is one which has manufactured and exploded a nuclear weapon or other nuclear explosive device prior to 1 January 1967.” Five states – China, France, Russia, the United Kingdom, and the United States – are in this category of nuclear weapons possessor states officially recognized by the NPT, and are generally referred to as the “nuclear-weapon states.” These five states are also the permanent members of the United Nations Security Council. Thus, the NPT may be said to have established a monopoly or legitimate right to possess nuclear weapons for states that already had such weapons before 1 January 1967. Although the NPT legitimized the nuclear arsenals of the above-mentioned five states, it also established that the nuclear-weapon states were not supposed to build and maintain nuclear weapons in perpetuity, (see Article 6, below). Besides the three nuclear-weapon states, who are members of NATO, the twenty-five other NATO members are so-called “nuclear-umbrella states,” i.e., countries protected by the nuclear weapons of the United States and the United Kingdom. Australia, Japan, and South Korea are also nuclear-umbrella states, in alliance with the United States.

All other states parties are non-nuclear-weapon states, which are not allowed to have nuclear weapons according to the NPT. Article 2 of the Treaty lays down the non-nuclear-weapon states’ obligations not to possess, manufacture, or receive nuclear weapons: “Each non-nuclear-weapon state party to the Treaty undertakes not to receive the transfer from any transferor whatsoever of nuclear weapons or other nuclear explosive devices or of control over such weapons or explosive devices directly, or indirectly, not to manufacture or otherwise acquire nuclear weapons or other nuclear explosive devices, and not to seek or receive any assistance in the manufacture of nuclear weapons or other nuclear explosive devices.”

The so-called nuclear-armed states are countries that are not parties to the NPT, and therefore not explicitly bound by the prohibition on nuclear weapons in Article 2. The three non-parties to the NPT and non-recognized nuclear-armed states are Israel, India, and Pakistan.

The NPT does not prohibit or limit the use of nuclear energy. According to Article 4, all the parties to the treaty have an inalienable right to develop research, production, and use of nuclear energy for peaceful purposes without discrimination and in conformity with Articles 1 and 2 of the treaty. Article 5 expands this right of access for all states to the peaceful use of nuclear energy, guaranteeing all participating non-nuclear-weapon states the potential benefits of any peaceful application of nuclear energy under appropriate international observation according to a special international agreement or agreements, through an appropriate international body. Such special international agreements have been concluded in the form of safeguards agreements with the International Atomic Energy Agency (IAEA).

As a condition of their agreement to adopting the NPT, the non-nuclear-weapon states demanded that the treaty should contain a provision for a general disarmament obligation that would apply to all parties. This was called the “grand bargain” of nuclear weapons possession and disarmament. In practice, of course, this obligation is only relevant for the nuclear-weapon states. Article 6 contains the following disarmament obligation: “Each of the parties to the Treaty undertakes to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control.”

This was the non-nuclear-weapon states’ “price” for giving up the development or acquisition of nuclear weapons. In return, the nuclear-weapon states committed themselves to negotiate disarmament of nuclear weapons – with a view to the complete abolition of these weapons. This commitment was re-established in Decision 2 on Principles and Objectives for Nuclear Non-Proliferation and Disarmament, which was adopted at the NPT Review Conference in 1995 and in which the nuclear-weapon states reaffirmed their commitment under Article 6 to disarmament of their nuclear weapons. In the Final Documents of the 2000 NPT Review Conference, the five nuclear-weapon states again committed themselves to “An unequivocal undertaking by the nuclear-weapon states to accomplish the total elimination of their nuclear arsenals leading to nuclear disarmament, to which all states parties are committed under article VI.”4

The NPT does not provide for a secretariat or an organization to monitor and ensure that the states parties comply with their obligations under the Treaty. This supervisory function is carried out by the IAEA in Vienna. NPT’s Article 3 stipulates, for example, that each non-nuclear-weapon state party to the treaty undertakes to accept IAEA safeguards, as set forth in an agreement to be negotiated and concluded with the IAEA – a so-called safeguards agreement. According to the IAEA safeguards agreement, the Agency’s inspectors may control that the participating states fulfill the obligations they have assumed under the Treaty with a view to preventing peaceful uses of nuclear energy from being diverted from nuclear power plants to the manufacture of nuclear weapons. All nuclear materials in all peaceful nuclear activities may be verified. Inspections of the civilian nuclear facilities include their fissile material (nuclear reactor fuel) for the production of nuclear energy. Nearly every state in the world (182 states) has concluded safeguards agreements with the IAEA, including Iran, North Korea, Israel, India, and Pakistan, and 127 states have concluded additional safeguards protocols with the IAEA. All the five nuclear-weapon states have concluded safeguards agreements and additional protocols with the IAEA to inspect their civilian nuclear facilities. The additional protocols supplement the states’ safeguards agreements by granting the IAEA expanded rights of access to information and sites. The additional protocols aim to fill the gaps in the information reported under the safeguards agreements. By enabling the IAEA to obtain a much fuller picture of the states’ nuclear programs, plans, nuclear material holdings, and trade, the additional protocols help to provide much greater assurance on the absence of undeclared nuclear material and activities. All the five recognized nuclear-weapon states, as well as India, have safeguards agreements and additional protocols in force with the IAEA for inspections of their civilian nuclear facilities, activities, and materials. Israel and Pakistan have only safeguards agreements. The military facilities of the nuclear-weapon states are not subject to IAEA inspections.

Article 3 further obliges each state party not to provide fissionable material, equipment, or material especially designed or prepared for the processing, use, or production of special fissionable material, to any non-nuclear-weapon state for peaceful purposes, unless the source or special fissionable material is subject to the safeguards required by the Article.

An NPT review conference is convened every five years to review the operation and implementation of the treaty, to ensure that the states parties comply with its provisions, and to ensure that its purposes are being realized (Article 8, paragraph 3).

The latest review conference was held in New York from 27 April to 22 May 2015. During the review conference the participants were deeply divided over whether the nuclear-weapon states have met their commitments under the NPT to reduce, and ultimately eliminate their nuclear arsenals. The nuclear-weapon states insisted on an incremental step-by-step approach for nuclear disarmament and rejected proposals from the non-aligned states to initiate negotiations on a convention to prohibit and eliminate nuclear weapons and to establish a standing body to monitor compliance with the NPT. It was also recommended by a great majority of non-nuclear-weapon states that the General Assembly should establish an open-ended working group to “identify and elaborate” effective disarmament measures, including a stand-alone agreement for achieving and maintaining a world free of nuclear weapons.5 However, the proposal also recommended that the working group should proceed by consensus, which would have given the nuclear-weapon states the ability to block any progress.

In the end, it was not possible to obtain consensus on a final outcome document from the review conference. This was mainly because the United States, Egypt, and the other Arab states disagreed on the modalities for convening a conference to establish a zone free of weapons of mass destruction in the Middle East, which had been agreed upon by the 2010 NPT Review Conference. The conference was to have been convened in 2012 but it was never held because of resistance from Israel, which insists that regional security issues must also be addressed, along with weapons of mass destruction issues. Therefore, Israel could not agree to the proposed agenda for the Middle East conference. On the last day of the 2015 Conference, the United States, the United Kingdom, and Canada stated that they could not accept the provisions in the draft final document on convening a conference to advance a zone free of weapons of mass destruction in the Middle East.

The 70th General Assembly adopted resolution 70/38, Follow-up to nuclear disarmament obligations agreed to at the 1995, 2000, and 2010 Review Conferences of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, by which the General Assembly “calls for practical steps, as agreed to at the 2000 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, to be taken by all nuclear-weapon states, that would lead to nuclear disarmament in a way that promotes international stability and, based on the principle of undiminished security for all.” Among the practical steps mentioned in the resolution are:

further efforts by the nuclear-weapon states to reduce their nuclear arsenals unilaterally,

further reduction of non-strategic nuclear weapons,

concrete agreed measures to further reduce the operational status of nuclear weapons systems,

a diminished role for nuclear weapons in security policies.

The resolution was adopted, with 121 votes in favour, 48 against, and 12 abstentions. France, Israel, Russia, the United Kingdom, the United States, and Canada voted against. China, India, Pakistan, and North Korea abstained.


The terrorist attacks against the United States on 11 September 2001 strongly intensified international concerns about terrorist organizations getting hold of nuclear, biological, chemical, and radiological weapons, materials, and technology. This led to the launch by the former Group of Eight (G8) countries – Canada, France, Germany, Italy, Japan, Russia, the United Kingdom, and the United States – at their summit in Kananaskis, Alberta, in June 2002, of the “Global Partnership against the Spread of Weapons and Materials of Mass Destruction.”6 The purpose of this security initiative was to prevent both state actors (so-called “rogue states,” i.e., irresponsible states that do not respect the rules of international law and norms) and non-state actors (terrorist organizations) from acquiring weapons and materials of mass destruction. Originally, the efforts under the Partnership were concentrated on the security and environmental threats from the huge numbers of weapons of mass destruction left in Russia after the end of the Cold War. Among the priority areas in Russia were the following tasks:

destroying chemical weapons stockpiles,

dismantling 192 decommissioned nuclear submarines,

securing and disposing of fissile materials,

re-employing former scientists in the weapons of mass destruction industry, and

destroying and preventing the proliferation of biological weapons.

The United States made a commitment of $10 billion to contribute to Partnership activities in Russia. The other G-8 countries pledged to contribute an additional $8 billion during a ten-year period. Other countries pledged to contribute 160 million Euros. A total of thirteen other countries, the European Union, and the Nuclear Threat Initiative have contributed to the Global Partnership, which was extended in 2011 until 2012–22.


In April 2004, the United Nations Security Council adopted resolution 1540, Non-proliferation of weapons of mass destruction. The resolution, adopted unanimously, expresses grave concern about the threat of terrorism and the risk that non-state actors could acquire, develop, traffic in, or use nuclear, chemical, and biological weapons and their means of delivery. In the resolution, the Security Council also expresses grave concern about the threat of illicit trafficking in nuclear, chemical, or biological weapons and their means of delivery, and related materials. This threat adds a new dimension to the issue of the proliferation of such weapons and also poses a threat to international peace and security. Acting under Chapter VII of the Charter of the United Nations, on what actions to take when there are threats to the peace, breaches of the peace, and acts of aggression, the Council “decides that all states shall refrain from providing any form of support to non-state actors that attempt to develop, acquire, manufacture, possess, transport, transfer, or use nuclear, chemical, or biological weapons and their means of delivery.” The Council also decides that “all states, in accordance with their national procedures, shall adopt and enforce appropriate effective laws which prohibit any non-state actor” from engaging in any of the above activities, in particular for terrorist purposes.

Furthermore, “all states shall take and enforce effective measures to establish domestic controls to prevent the proliferation of nuclear, chemical, or biological weapons and their means of delivery.”

To this end, all states shall “develop and maintain appropriate effective measures to account for and secure production, use, storage, or transport of such items” as well as physical protection and border controls. Law enforcement efforts shall be taken to “detect, deter, prevent, and combat the illicit trafficking and brokering in such items.” States are called upon to report to the “1540 Committee,” set up by the Security Council, on the steps they have taken or intend to take to implement the resolution. The Committee’s mandate has been extended to 2021.

In several other resolutions, the Security Council, acting under Chapter VII of the Charter, has taken measures under Article 41 to impose sanctions (“measures not involving the use of armed force”) “to be employed to give effect to its decisions.” Many of these resolutions have imposed arms sales embargoes to prevent supplying, selling, or transferring in any way all types of conventional weapons covered by the United Nations Register of Conventional Arms. Member states have also been called upon to take all necessary measures to prevent transfers of materials and technology that could be used for nuclear weapon programs and missiles, e.g., to North Korea and Iran.7

At a historic meeting of the Security Council on 24 September 2009, attended by President Obama and thirteen other heads of state, the Security Council unanimously adopted resolution S/RES/1887 (2009), Maintenance of international peace and security: Nuclear non-proliferation and nuclear disarmament. The resolution contains a number of paragraphs on a wide range of steps for member states to take in order to, for example, stop the spread of nuclear weapons, ensure reductions in existing stocks of nuclear weapons, and controlling fissionable materials.

On 26 September 2013, the General Assembly held a high-level meeting on nuclear disarmament.8 The 70th General Assembly adopted resolution 70/36, Measures to prevent terrorists from acquiring weapons of mass destruction, by which the General Assembly “calls upon all member states to support international efforts to prevent terrorists from acquiring weapons of mass destruction and their means of delivery,” and further “urges all member states to take and strengthen national measures, as appropriate, to prevent terrorists from acquiring weapons of mass destruction, their means of delivery and materials and technologies related to their manufacture.” The resolution was adopted without a vote.


Since the 2001 terrorist attacks on the United States, the physical security of nuclear power plants and their vulnerability to deliberate acts of terrorism by aircraft crashing into nuclear reactors or through sabotage or theft of nuclear materials, has become an issue of increasing concern. Most existing nuclear power plants are not designed to withstand crashes from large aircraft. A successful attack on a nuclear plant could have devastating consequences, killing, sickening, or displacing large numbers of residents in the area surrounding the plant, and causing extensive long-term environmental damage. Cyberattacks on nuclear power plants could also have devastating consequences. Uranium enrichment plants or uranium mines and civilian research reactors are also vulnerable to attacks, which could lead to widespread radioactive contamination.

The foreword to the NTI (Nuclear Threat Initiative) report Bridging the Military Nuclear Materials Gap, November 2015,9 states: “One of the greatest threats the world faces is the possibility that a terrorist group could acquire and detonate a nuclear weapon or device. A terrorist nuclear attack in any large city would likely kill hundreds of thousands of people, inflict billions of dollars in damage, and have profound effects on global security, the global economy, and our way of life. The effects of such an attack would no doubt transcend national boundaries, thus compelling a global response to a global threat.”

According to this report, more than 1,800 metric tons of weapons-usable nuclear materials – highly enriched uranium and plutonium – remain stored today in hundreds of facilities, some of them poorly secured and vulnerable to theft, in twenty-four countries around the world. Recent security breaches and incidents at nuclear facilities show that governments must do more to secure these dangerous materials and keep them out of the hands of terrorists. There is still no effective global system for how all weapons-usable nuclear materials should be stored. The existing mechanisms apply almost exclusively to a small part of all these materials – the 17 per cent used for peaceful, civilian purposes. The remaining 83 per cent are military nuclear materials outside the scope of existing international security standards that must apply to all nuclear materials that could be used by terrorists to build a nuclear device. The report therefore recommends strengthening the security of military materials in order to secure all nuclear materials, including military materials, and facilities; strengthening tools to detect and prevent the trafficking of nuclear materials across borders; and strengthening international cooperation on intelligence and law enforcement.

Experience shows that nuclear power plants – and even military nuclear facilities – are, in general, not sufficiently protected against intrusion, sabotage, or attack. One of the most spectacular incidents, considered the biggest security breach in the history of US atomic installations, is the break-in at the nuclear weapons plant at Oak Ridge, Tennessee, where the United States keeps thousands of kilograms of highly enriched uranium and parts for nuclear weapons. In July 2012, Sister Megan Rice, an 82-year-old nun, and two other peace activists cut through three fences before reaching a storage bunker. Although the protesters set off alarms, they were able to spend nearly an hour and a half inside the restricted area before they were arrested for trespassing! There have been other security breaches at military facilities where American nuclear missile launch officers and British law enforcement personnel at a nuclear weapons site were found sleeping and not completing patrols. There have also been incidents of intrusion into and theft of fissile material from nuclear power plants.

Illicit trafficking and smuggling of radioactive nuclear materials continue at an alarming rate. Since 1993, the IAEA has registered approximately 2,000 cases of illicit or unauthorized trafficking of nuclear and other radioactive material. In at least eighteen cases there have been confirmed thefts or losses of weapons-usable nuclear material.10 Moldova has experienced three incidents, in 2011, 2014, and in February 2015, when smugglers transported radioactive materials by train from Russia and tried to sell these materials.

Against the background of growing international attention to the global threat posed by nuclear terrorism, and at the initiative of President Obama, world leaders from forty-seven countries and three international organizations gathered for the first Nuclear Security Summit in Washington in April 2010. In the communiqué from the Washington Summit, the participating leaders expressed their commitment to ensuring the effective security of all nuclear materials under their control, to consolidate or reduce the use of weapons-usable materials in civilian applications, and to work cooperatively as an international community to advance nuclear security. Leaders reaffirmed states’ fundamental responsibility to maintain effective security of all nuclear materials, including nuclear materials used in nuclear weapons and nuclear facilities under states’ control, and to prevent non-state actors from obtaining the information or technology required to use such material for malicious purposes. A second Nuclear Security Summit was held in Seoul in March 2012, and a third in The Hague in March 2014. A comprehensive summit communiqué on a wide range of measures to address the threats of nuclear terrorism was issued from The Hague meeting.11 The fourth and probably final Nuclear Security Summit was held in March–April 2016, in Washington, DC.

Because the Nuclear Security Summit process will came to an end after the 2016 summit in its current form, a small group of four experts, members of the Nuclear Security Governance Experts Group, a project of the Asian Institute for Policy Studies, the Partnership for Global Security, and the Stanley Foundation, drew up a draft of an International Convention on Nuclear Security, which was presented in Washington in March 2015.12

This Convention would establish basic principles and standards for nuclear security and create mechanisms for additional rules. The objective of the Convention is “to ensure effective security of nuclear and other radioactive materials by codifying a set of essential elements for national nuclear security regimes and establishing a mechanism for continuous review and improvement of the international nuclear security regime” (Article 1). “Nuclear security” is defined in the Convention as “the prevention and detection of, and response to, theft, sabotage, unauthorized access, illegal transfer or other malicious acts involving nuclear and other radioactive materials or their associated facilities and equipment” (Article 2). Article 3 determines the scope of the Convention, which “shall apply to all nuclear and other radioactive materials used for civil purposes and the facilities in which they are contained and, to the extent possible, to such materials and facilities used for non-civil purposes.”13

Such a Convention would fill the dangerous gaps in the current inadequate nuclear security regime and create an effective and sustainable global nuclear security system to prevent nuclear terrorism. The Convention would supplement the Convention on Nuclear Safety,14 of 1994, whose aim is to commit the (78) participating states operating nuclear power plants to maintain a high level of safety to avoid nuclear radiation accidents by setting international standards for the location, siting, design, construction, and operation of nuclear installations.

The Nuclear Security Convention would expand the Convention on the Physical Protection of Nuclear Material, signed in March 1980 (153 states parties) and the International Convention for the Suppression of Acts of Nuclear Terrorism of 2005. The Convention on Nuclear Terrorism has been ratified by 115 states, including all the nuclear-weapon states and India. Israel has signed, but not ratified the Convention. Pakistan, Iran, and North Korea have neither signed nor ratified it. According to the Convention, nuclear terrorism is

unlawfully and intentionally possessing or using radioactive material or a nuclear device,

causing damage to a nuclear facility and releasing radioactive material in order to cause death,

causing serious bodily injury or substantial damage to property or to the environment.

The Convention exempts the use of nuclear weapons in armed conflicts between states from this definition.


The Proliferation Security Initiative (PSI) was launched by the United States in May 2003 as an international effort to prevent and stop the spread of weapons of mass destruction. The purpose of the PSI is to stop illegal transfers of weapons of mass destruction and technology, related materials, and delivery systems for WMD. The PSI activities include planning, exercises, and operations. The effort, which is based on the rules in international law and national legislation, may include interception and boarding of ships, aircraft, trains, and trucks transporting weapons of mass destruction, as well as the inspection of goods in containers in ports and airports, thereby preventing the proliferation of WMD. Thus, the PSI also includes cooperation between custom and police authorities. Many countries with large merchant fleets registered under flags of convenience, including Liberia and Panama, have signed agreements with the United States on joint operations in connection with the boarding of ships under their flag.

The PSI is not a formal, legally binding regime or organization, but a pragmatic group of states that support activities at sea, in the air, and on land to prevent the spread of weapons of mass destruction. The basic principles of the PSI, were committed to by the participating states, and adopted in September 2003. They include commitments to establish a more coordinated and effective basis on which to impede and stop shipments of WMD, delivery systems, and related materials flowing to and from states and non-state actors. These commitments must be consistent with national legal authorities and relevant international law and frameworks, including the United Nations Security Council.15

All countries and international organizations can participate in the proliferation regime. A total of 105 countries have joined the Initiative. China, Iran, North Korea, Syria, India, Pakistan, and Indonesia, among other states, are not participating in the PSI. Several of the countries that are not participating in the cooperation under the Initiative claim that the stopping and boarding of ships on the high seas is a violation of freedom of navigation on the high seas (Article 87 of the Convention on the Law of the Sea). These countries have also criticized the PSI for being a US-led, illegal, and non-transparent initiative that is not based on United Nations resolutions, and whose purpose is to seize ships of third-party countries on the high seas.



To be sure that a nuclear weapon works and can be used as a deterrent, tests of a newly developed nuclear weapon need to be carried out.

Since the first American nuclear test on 16 July 1945 in the Alamogordo desert in New Mexico until July 1996, the five recognized nuclear-weapon states have carried out a total of 2,047 nuclear tests.16 The Soviet Union conducted its first test of an atomic bomb on 29 August 1949, thus initiating the nuclear weapons arms race between the United States and the Soviet Union. The United Kingdom, France, and China conducted their first test explosions of nuclear bombs in 1952, 1960, and 1964 respectively.

Between 1945 and 1992, the United States carried out a total of 1,032 nuclear tests. In November 1952, the United States became the first country to test a hydrogen bomb. The test explosion, which took place at the Bikini Atoll in the Marshall Islands, yielded 15 megatons – equivalent to 15 million tons of TNT – and was the largest nuclear weapon ever detonated by the United States. By comparison, the nuclear bomb dropped over Hiroshima and Nagasaki had a yield of approximately 15 and 20 kilotons respectively – equivalent to 15 and 20 thousand tons of TNT, respectively. The total energy yield of all explosives used in the Second World War, including the Hiroshima and Nagasaki bombs, is estimated to have been 3 megatons.

The Soviet Union/Russia conducted a total of 715 nuclear tests between 1949 and 1990. From 1952 to 1991, the United Kingdom made forty-five nuclear tests. France carried out 210 nuclear test explosions between 1960 and 1996, and China forty-five tests between 1964 and 1996. India conducted its first nuclear test in 1974. In May 1998, India carried out two more tests. Two weeks later, Pakistan tested a nuclear weapon for the first time.