U.S. Secretary of State John Kerry leaves the stage at the Vienna International Center in Vienna, Austria on July 14, 2015 during talks in which Iran and six major world powers reached a nuclear deal.

The number of nuclear weapons in the world has shrunk since its peak in the 1980s; however, there are more countries with nuclear weapons than ever before.

Nine states are known or believed to possess nuclear weapons: the United States, Russia, France, China, the United Kingdom, Pakistan, India, Israel, and North Korea. Several other countries started nuclear weapons exploration programs but gave them up, either voluntarily or because of pressure from other countries. A few have had nuclear weapons and later destroyed them or turned them over to another nuclear armed state.

Though the exact number of nuclear weapons held by each country is not publicly available, analysis of historical records and occasional leaks provides a generally accurate picture of a country’s nuclear arsenal.

Approximately 93% of all nuclear warheads belong to either the United States or Russia, with each having roughly 4,000 in their military stockpiles.

The World's Nuclear Arsenals

During the Cold War, the United States and the Soviet Union dominated nuclear politics, amassing some 60,000 weapons in total. Nuclear annihilation was an acute fear, with both nations possessing enough nuclear weapons to destroy each other several times over. Today, the nuclear landscape has expanded, with the potential for catastrophic conflict dispersed between more countries.

CURRENT THREATS

Nuclear conflict involving any of the first five nuclear powers – the United States, Russia, the United Kingdom, France, and China – is unlikely, but still remains a possibility. Although the number of weapons held by these countries has declined, most are reluctant to engage in disarmament talks because they see nuclear weapons as important components of their security strategies.

Though Israel has never confirmed its status as a nuclear weapons state, it is believed to possess a considerable number of nuclear weapons. It is not a party to the Treaty of the Nonproliferation of Nuclear Weapons (NPT), but it has taken action to stop nearby countries from building a nuclear arsenal. Israel bombed suspected nuclear reactor sites in Iraq (1981) and Syria (2007). It has also signaled that it would attack Iran if it feels threatened by the country’s nuclear program. However, a 2015 deal between Iran and the United States, China, France, Russia, the United Kingdom, Germany, and the European Union limited Iran’s nuclear development and eased some of this international tension. Though this is not necessarily a long-term solution, as the deal’s terms will start expiring in 2025.

Sharing an 1,800-mile border, India and Pakistan have fought several conventional wars over 100,000 square miles of disputed territory. Now, both countries possess nuclear weapons. Neither is party to the NPT, and they both appear to be modernizing and increasing their stockpiles. While many policymakers and experts fear nuclear war could break out between the two countries, they are also concerned that Pakistan could lose control of a nuclear weapon to terrorists.

North Korea poses the biggest nuclear threat. It withdrew from the NPT in 2003 and conducted its first nuclear test in 2006. The country has threatened to use its nuclear weapons against the United States, South Korea, and Japan. Although the country is believed to have a small arsenal, its continued nuclear tests and aggressive behavior have raised widespread concerns over possible nuclear conflict.

Timeline of Nuclear Weapons States

SECURITY GUARANTEES

Security guarantees are pledges from one country to protect an ally’s security. A country with nuclear weapons can provide such a guarantee by suggesting it might use its weapons against a country that attacks its ally. This puts the ally under the protecting country’s “nuclear umbrella.” The purpose is to deter attacks by making an outside power believe that it could face nuclear retaliation even if it attacks a country that does not possess nuclear weapons.

Nuclear Umbrellas

See which countries fall under the U.S. and Russian "umbrellas"

The term “nuclear umbrella” generally refers to the nuclear security guarantees between the United States and other countries, notably the NATO member countries plus Australia, Japan, and South Korea. (Two other NATO members, France and the United Kingdom, have nuclear weapons of their own.) Additionally, some consider the Collective Security Treaty Organization – a military alliance between Russia and the non-nuclear-weapon countries of Armenia, Belarus, Kazakhstan, Kyrgyzstan, and Tajikistan – to be an informal nuclear umbrella as well.

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