• How many countries have nuclear weapons and how many are there?

    Nine countries - China, North Korea, France, India, Israel, Pakistan, Russia, the United Kingdom and the United States - possess a total of nearly 13,080 nuclear weapons. Russia and the United States possess roughly 90% of the world’s nuclear weapons, with over 5,500 weapons each. Learn more

  • How destructive are today’s nuclear weapons?

    The  two nuclear weapons dropped on Hiroshima and Nagasaki, had an explosive yield of the equivalent of about 15 kilotons of dynamite and 20 kilotons of dynamite respectively. In modern nuclear arsenals, those devastating weapons are considered “low-yield.” Many of the modern nuclear weapons in Russian and U.S. nuclear weapons are thermonuclear weapons and have explosive yields of the equivalent at least 100 kilotons of dynamite - and some are much higher. One 100-kiloton nuclear weapon dropped on New York City could lead to roughly 583,160 fatalities, according to NukeMap

  • What about “nuclear deterrence” theory? Do nuclear weapons help keep the peace?

    Nuclear deterrence doesn’t work. Here’s why.

    1. We aren’t rational and we can’t read minds. For nuclear deterrence to work, all stakeholders must be perceived to act “rationally” and “predictably” but we know that’s not how people work - particularly in the fog of war.  

    2. Nuclear weapons don’t keep the peace. History shows that the existence of nuclear weapons has done nothing to prevent the many terrible conflicts since 1945, including acts of aggression against countries with nuclear weapons. In reality, nuclear weapons haven’t been used due solely to good luck – which cannot be expected to last forever.

    3. Nuclear weapons make conflicts worse. The 2022 Russian invasion of Ukraine highlights how any of the 9 nuclear-armed states can threaten or use nuclear weapons to limit the capacity of other states to respond. 

    4. Nuclear deterrence makes nuclear use more likely because the threat of use of nuclear weapons must be credible, and so the nuclear armed states are always poised to launch nuclear weapons.

    5. Nuclear weapons are useless for today’s threats. Nuclear weapons are strategically useless to address the actual security threats facing nations in the 21st century, including climate change, terrorism and cyber attacks. 

  • What is the New START Agreement and why has Russia suspended its implementation?

    In February 2023, Russian President Vladimir Putin announced the suspension of Russia's implementation of New START (Strategic Arms Reduction Treaty). This bilateral treaty between the US and Russia limits both countries to 1,550 deployed strategic nuclear warheads on 700 deployed nuclear missiles and bombers.

    Russia already stopped allowing inspections of nuclear weapons sites and participation in a bilateral consultative commission. In his speech announcing the decision, Putin declared that the treaty could not be kept separate from the war in Ukraine and “other hostile actions of the west against our country”. However, Russia’s foreign ministry has declared that it will continue to observe limits on the number of nuclear warheads it can deploy under the New START and maintain crucial communication of ICBM missile tests.

    This suspension is dangerous and reckless - Russia must immediately return to full compliance with the agreement and continue to adhere to its nuclear weapon limits while pursuing disarmament. It also demonstrates why bilateral agreements will not be enough to guarantee disarmament and reduce nuclear risk. The world needs the nuclear-armed states to take real steps towards joining the global, comprehensive multilateral agreement to eliminate nuclear weapons: the UN Treaty on the Prohibition of Nuclear Weapons.

  • What is the Treaty on the Prohibition of Nuclear Weapons?

    The Treaty on the Prohibition of Nuclear Weapons was adopted in July 2017 at the United Nations with 122 countries voting in favor. It bans the use, threat of use, development, production, manufacture, acquisition, possession, stockpiling, transfer, stationing, deployment or installation of nuclear weapons, as well as assistance with, encouragement or inducement of any of these prohibited activities. The treaty also includes positive obligations requiring states parties with people or places harmed by nuclear weapons use or testing under their  jurisdiction to provide assistance and requires all states parties in a position to do so to also help these efforts. The treaty strengthens the norm against nuclear weapons as the first legal instrument to ban them.

  • Why does this treaty matter if none of the countries with nuclear weapons have joined?

    The Treaty on the Prohibition of Nuclear Weapons is a powerful normative tool to demonstrate that nuclear weapons are morally unacceptable. It strengthens the legal framework and legal stigma against nuclear weapons. The TPNW can put external pressure on nuclear-armed states to make further efforts on disarmament. 

    The TPNW  reinforces other disarmament efforts by nuclear-armed states, such as the ratification of the Comprehensive Test Ban Treaty, further reductions of arsenals, and de-alerting nuclear weapons systems. The TPNW does not preclude or prevent bilateral or multilateral agreements to reduce numbers of warheads between nuclear-armed states.

  • Why should one country give up its nuclear weapons if other countries still have them?

    Nuclear weapons pose unacceptable risks to humanity and the environment. The vast majority of the world’s nations have already chosen to contribute to a world without nuclear weapons by rejecting ever developing, possessing or using them as members of Nuclear- Weapons-Free-Zones. The vast majority of the world’s countries already recognize that nuclear weapons make them less safe, not more secure. It is time for the nine nuclear-armed states to get on board.

  • Why should countries that don’t have nuclear weapons care about this treaty?

    The possession of nuclear weapons by some states puts the whole world at risk. Strengthening the norm against the use and possession of nuclear weapons is in the interest of all states and people.

    Beyond banning and working towards the total elimination of nuclear weapons, the Treaty on the Prohibition of Nuclear Weapons contains important positive obligations for countries to receive and provide victim assistance for impacted people and environmental remediation for places impacted by nuclear weapons use and testing. The TPNW can help to ensure that affected communities receive the assistance they need.

  • Can a NATO state join the TPNW?

    According to research by the Norwegian People’s Aid, a NATO state can join the TPNW and be in compliance with the treaty as long as “they explicitly distance themselves from specific statements or formulations in Alliance documents, particularly the Strategic Concept, which can be understood as an encouragement of the retention of nuclear weapons and their possible use.” Without doing so, the NPA report finds that NATO states would be in violation of Article 1(1)(e) of the treaty.

  • Did Ukraine give up nuclear weapons?

    When the Soviet Union broke up in 1991, there were thousands of former Soviet nuclear warheads, as well as hundreds of intercontinental ballistic missiles and bombers, left on Ukraine’s territory, which it decided to transfer to Russia. Ukraine never had an independent nuclear weapons arsenal, or control over these weapons, but agreed to remove former Soviet weapons stationed on its territory. In 1992, Ukraine signed the Lisbon Protocol and it joined the Nuclear Non-Proliferation Treaty as a non-nuclear weapon state in 1994. The transfer of all nuclear material took some time, but by 2001, all nuclear weapons had been transferred to Russia to be dismantled and all launch silos decommissioned.

    While some may ask if Russia would have invaded Ukraine if it still had Soviet nuclear weapons stationed on its territory, there is little convincing historical evidence that the possession or presence of nuclear weapons definitively prevents conflict, when many other variables may be considered, including the prohibition of the use of force under the UN Charter or even just luck. Even beyond this, it is not clear that Ukraine would have been able to take control of former Soviet nuclear weapons, technically or politically. What we do know is that the possession of nuclear weapons by Russia and the United States clearly has not prevented the threat of conflict between Russia and a U.S. ally or the potential humanitarian consequences of any conflict for civilians in the region. Read more about Ukraine and nuclear weapons.

  • What are "tactical" nuclear weapons?

    Technically, a tactical nuclear weapon is any weapon that’s not been classified as “strategic” under US- Russian arms control agreements (SALTSORTSTART). Deployed tactical weapons in Europe can have explosive yields up to 300 kilotons, or 20 times that of the bomb that destroyed Hiroshima. Sometimes these weapons are also referred to as  ‘sub-strategic’ or ‘non-strategic’.  


    Most frequently, ‘tactical’ nuclear weapons imply the weapons that were designed to be used on the battlefields of Europe during the Cold War. In the last century, they were deployed across the continent in case a 'hot' conflict between NATO and the Warsaw Pact were to escalate. At the end of the 1980s there were around 7,500 of these weapons deployed throughout Europe, but the mutual unilateral reductions that took place in the early 1990s brought the numbers down significantly. The Federation of American Scientists currently estimates Russian non-strategic nuclear warheads at 1,912, and approximately 100 U.S. non-strategic warheads deployed in five European countries. 


    For more on the impacts of any nuclear weapon, see here.

  • What are 'dirty bombs'?

    A dirty bomb, or a radiological weapon, is one in which nuclear material is combined with traditional explosives into a bomb.  The detonation is a conventional one- it’s not a nuclear explosion which releases a huge amount of energy by splitting the atom- but it is still an explosion that can disperse radioactive material. As the explosion is not as large as with a nuclear bomb, any radioactive material is unlikely to reach the upper atmosphere to become fallout.  A dirty bomb is not a nuclear weapon or a nuclear explosive device. The effects of a dirty bomb in terms of the anxiety and fear it causes can be tremendous. This is why a dirty bomb is also dubbed a weapon of mass disruption.


    What are some impacts?

    Researchers have looked at various impacts of chemical or biological weapons use by terrorist groups to assess what might happen if a radiological weapon were detonated. For example, the 1995 Sarin attack by the Aum Shinrikyo cult showed widespread panic and fear.

    Another example is the incident in 1987 in Goiania in Brazil, where a Cesium-137 source was found and opened by scrap-metal scavengers in an abandoned radiotherapy institute.  The material was used in paint, and the dust spread over the area, contaminating more than 400 persons over the next two weeks. Four of those died from the exposure. To mitigate further damage, more than 100,000 people needed to be tested, and there was long-lasting social stigma to the area in which the incident occured. 

    Another comparison was to look at the disaster of Chernobyl. Although the situation is very different from a dirty bomb scenario, it did show how radioactive materials, and specifically cesium, attaches itself to an urban environment and what those consequences are for the surrounding population. 


    What is the response capacity?

    Most emergency services have protocols in place for “CRBN” (Chemical, Radiological, Biological and Nuclear) emergencies, and to deal with the situation a number of phases are identified: the period before an attack, shortly after and some time after the attack. 

    Before an attack the radiological source can already emit radiation but it is most likely that this will only affect the terrorist themselves or close bystanders. In the phase immediately after the attack it is necessary to attend to wounded persons and stabilize them first before starting decontamination, while rescue-workers at the same time need to take measures for personal protection. 

    Because debris can work as a hotspot for radiological material the cleaning process needs to be started as soon as possible. Any cloud created by the explosion has the ability to carry radioactive particles and spread the material which will attach itself to buildings, grass and streets. It is necessary to start monitoring the cloud to determine which areas are contaminated and need to be cleaned.


    Is there any international regulation on a dirty bomb?

    There is a global effort to secure nuclear materials to prevent their use in any sort of improvised radiological weapon. There are international agreements, like the Convention on the Physical Protection of Nuclear Materials, the International Convention for the Suppression of Acts of Nuclear Terrorism, and a series of UN Security Council resolutions (including 1373 and 1540). There are also informal mechanisms, like the Global Partnership Against the Spread of Weapons and Materials of Mass Destruction and the outcomes from the Nuclear Security Summit Processes which were non-binding commitments to convert highly enriched uranium facilities to low enriched uranium, and to put excess materials under global control.

    A dirty bomb is NOT a nuclear weapon and it is NOT a nuclear explosive device.  Therefore, it is not covered under either the NPT or the TPNW. 


    What can I do?

    Consistent and unequivocal condemnation from governments and civil society can stigmatise and delegitimize threats, help restore and strengthen the norm against the use of radiological weapons or dirty bombs, and reinforce nuclear security, disarmament and non-proliferation efforts. The use or threat of use of any chemical, biological, radiological or nuclear weapon is illegitimate and should be condemned.

  • What is the nuclear test ban treaty and why has Russia revoked its ratification?

    The Russian parliament has voted to revoke the country's ratification of the Comprehensive Test Ban Treaty (CTBT). Here is what we know:


    The Comprehensive Test Ban Treaty, adopted in 1996, is the first international treaty adopted to ban all nuclear tests. It has 187 states which have signed, and 178 which have ratified, but has not entered into force yet because of the failure of eight states, upon whose ratification the entry into force of the treaty depends: China, the Democratic People’s Republic of Korea, Egypt, India, Iran, Israel, Pakistan and the United States. Having revoked its ratification, Russia has returned to signatory status.


    On 6 October, President Putin stated the rationale for this decision when he said that in regards to the CTBT he sees it fit to “mirror the manner of the United States,” which has signed but not ratified the treaty, and revoke Russia’s ratification. He added that “this is a question for the State Duma [lower house of the Federal Assembly of Russia] deputies. In theory, this ratification could be revoked.”  


    On 9 October, the Duma’s Committee on International Affairs was instructed to contact the Russian Foreign Ministry to look into the issue of withdrawing the ratification of the CTBT. According to the State Duma’s press service, the conclusions must be presented by 18 October, 2023. On 10 October, Russian media reported that the Foreign Ministry was drafting a bill for Russia to revoke Article 1 of the 2000 law through which Russia ratified the CTBT, while retaining Russia’s cooperation with the International Monitoring System and Comprehensive Test Ban Treaty Organization which verifies compliance with the accord.  The draft bill was first introduced to the Duma on 17 October, passing a unanimous vote on its first reading, by 412 to zero with no abstentions. This was followed by two unanimous votes on the second and third readings of the bill on 18 October and the upper house will now formally approve it to make it law. 


    Russia weakening its commitment to the CTBT is senseless and irresponsible behaviour, and is  part of a pattern of Russia using nuclear weapons to intimidate opponents of its invasion of Ukraine. International treaties, including the CTBT and the TPNW, are critical to making sure nuclear testing that has harmed people’s health and spread lasting radioactive contamination is not resumed.


    Russia’s action undermines the global norm against nuclear testing, which all states – except for North Korea – have upheld for a quarter of a century. The erosion of this norm is in no state’s interests.


    Russia has a responsibility to re-ratify the treaty, and those outliers that have not yet signed or ratified the CTBT or TPNW need to get on board.

  • What are space nuclear weapons?

    The capability to deploy nuclear weapons into space is explicitly prohibited in the 1967 Outer Space Treaty. Detonating a nuclear weapon in space would create an electromagnetic pulse that would damage satellites indiscriminately, unless they are specially hardened, and create a tremendous amount of debris which could cause additional damages. The effect of a nuclear explosion in space on spacecraft was demonstrated in 1962 by the U.S. Starfish Prime test and led to the 1963 Limited Nuclear Test Ban Treaty.

    Low earth orbit is used by commercial satellites for many purposes - from communications to transportation to weather forecasting. There are a number of disruptive technologies that could impact satellites- from kinetic anti-satellite weapons (ASAT) (which would physically destroy the satellites), to signal jamming spacecraft, which could make existing satellites useless.

    Anti satellite weapons (ASAT) tests have been conducted by China, Russia and the United States. In February 2024, there was increased attention on this type of weapon following news reports  that Russia may be developing a nuclear weapon that can be deployed into space. In 2022 the United States pledged not to conduct destructive anti-satellite tests. For more than three decades there have also been discussions in the UN Committee on Peaceful Uses of Outer Space and the Conference on Disarmament.