What Countries Have Nuclear Weapons?

On October 6, 2006, North Korea announced it had detonated a nuclear bomb—making it the ninth nation to admit doing so. It wasn’t supposed to be that way. Until 2003, that country had been like all but a handful of countries, bound by the 1968 U.N. Non-Proliferation Treaty (NPT). That treaty allows peaceful nuclear technologies, but limits nuclear weapons to five nations: the United States, the Soviet Union (now Russia), the United Kingdom, France and the People’s Republic of China.

At its most stringent definition, the so-called ‘Nuclear Club’ has been limited to those five. Since 1971, they have also been the only members of the U.N. Security Council to hold permanent seats and veto power. Of the countries that never joined the NPT, four countries are believed to also have nuclear weapons. India and Pakistan have publicly acknowledged testing their own nuclear weapons, and Israel is widely assumed to have a significant arsenal. Along with North Korea, their programs are a testament to both the successes and failures of efforts to curb nuclear proliferation.

On July 16, 1945, at 5:29 a.m. a bright flash illuminated the New Mexico desert—and the world was never the same. The Trinity test of the first functional nuclear fission-powered weapon was the work of the World War II-era Manhattan Project. Less than a month later, on August 6 and 9, U.S. warplanes dropped atomic bombs over Hiroshima and Nagasaki, Japan, in attacks that hastened the end of World War II, but at a cost of more than 200,000 lives.

After the war, the U.S. kept the details of its bomb-making knowledge to itself, but both allies and rivals raced to develop their own weapons with their own scientists. On August 29, 1949, the Soviets detonated an atomic bomb, ensuring that the emerging Cold War would unfold under the threat of nuclear war.

Three years later, the British tested their homegrown atomic bomb; and days later, the U.S. tested the first hydrogen bomb at Eniwetok Atoll, in an explosion a thousand times more powerful than the one that had devastated Hiroshima.

By the time France (1960) and communist China (1964) had completed their own test detonations, international efforts were underway to limit the powerful new weapons’ spread. In September of 1958, Irish foreign minister Frank Aiken had introduced a resolution at the U.N. General Assembly to prohibit “further dissemination of nuclear weapons.”

Following the 1962 Cuban Missile Crisis, in which the world narrowly avoided a U.S.–Soviet nuclear exchange, the two superpowers plus Britain began negotiating the Limited Test Ban Treaty (LTBT), whose parties agreed to cease all nuclear tests in the atmosphere, underwater or in outer space. Eventually 122 additional nations joined the treaty.

The agreement represented the nuclear powers’ attempts to slow the development and proliferation of atomic weapons, but the 1967 Treaty of Tlatelolco, signed in Mexico City, became the first significant nuclear accord created by non-nuclear nations—in this case, every country in Latin America and the Caribbean except Cuba—agreeing they would not seek to join the Nuclear Club.

Just over a year later, the U.N.’s Non-Proliferation Treaty was opened for signature, setting global guidelines to limit military nuclear technology to the five nations known to have the bomb, while providing paths and inspection processes for all nations to legally develop and share peaceful nuclear technologies. Two years later, it went into force.

The NPT was largely—but not fully—a success. In The Nuclear Club: How America and the World Policed the Atom from Hiroshima to Vietnam, historian Jonathan R. Hunt writes that the NPT and other treaties mostly achieved their goal of limiting proliferation and preventing nuclear exchanges. But they also enforced what he describes as the correlation “between the stability that nuclear deterrence has enforced—the non-occurrence of shooting wars between nuclear-club members—and the frequency of civil wars, proxy conflicts, and territorial disputes for those outside its ranks.” Bloody Cold War conflicts in Asia, Africa, the Middle East and Latin America were all, at least in part, ways for the superpowers to push for dominance while limiting the risk of nuclear escalation.

The first nuclear explosion to come from outside the Nuclear Club went off on May 18, 1974, when India detonated what it termed a “peaceful nuclear device” in the desert of Rajasthan. The test bolstered India’s status as a nation forging its own way between the U.S. and Soviet spheres of influence, and its rivalry with nuclear-armed China, with whom it had fought two border wars in the 1960s.

Since at least the late 1960s, Israel has been assumed to be working on its own nuclear weapons. By the 1970s, the general view in the intelligence community was that Israel had a nuclear arsenal but preferred to avoid saying so directly. An intriguing pair of flashes observed by a U.S.-operated Vela satellite in 1979 over the southern Indian Ocean may have been the sign of a secret Israeli test of a nuclear device.

When the Soviet Union collapsed in 1991, concern grew over the potential for stolen “loose nukes” and other types of proliferation. Newly independent Kazakhstan and Ukraine quickly transferred their nuclear caches back to Russia, which had taken over the old Soviet seat on the U.N. Security Council.

During the Cold War, South Africa had managed to build six nuclear weapons, possibly with Israeli support, but its final Apartheid government preemptively dismantled and destroyed its arsenal in the run-up to the country’s first free elections in 1994.

The reduction of nuclear powers didn’t last, though. In May 1998, India conducted its second nuclear test—this time of a weaponized bomb. Two weeks later, their rival Pakistan responded with its own test. North Korea, which had joined the NPT in 1985, withdrew from it in 2003 and conducted its first nuclear test three years later.

In recent years, Iran has been considered the country coming closest to building its own bomb. Its domestic nuclear research initiative, which dates to President Dwight Eisenhower’s technology-sharing “Atoms for Peace” program, has long had public and covert tracks. In 2002, it was revealed that Iran had secretly been enriching uranium with the goal of making a bomb. Following international negotiations, the country suspended enrichment—only to restart it again three years later.

Since then, the U.N., Britain, France and Germany have attempted to work for a negotiated solution. Meanwhile, Israel, which sees a nuclear-armed Iran as an existential threat, has used cyberattacks, sabotage, assassination of scientists and military strikes to attempt to stall or turn back Iran’s progress towards having its own nuclear weapons.