How many nuclear bombs have been used?

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On July 16, 1945, the United States carried out the world’s first nuclear bomb test in the New Mexico desert under the Manhattan Project. Just weeks later, atomic bombs were detonated over Hiroshima and Nagasaki. Since then, at least seven additional nations have conducted their own nuclear tests, releasing radioactive fallout across the globe.

How many nuclear bombs have actually been detonated?

Although the precise total remains unknown, scientists estimate that at least 2,056 nuclear weapons have been tested. According to the Arms Control Association, the United States has conducted 1,030 tests and used two weapons in combat. The Soviet Union/Russia has carried out 715 tests, France 210, the United Kingdom and China 45 each, North Korea six, India three, and Pakistan two. A suspected additional test, known as the Vela incident, would raise the overall count to 2,057.

Although large-scale nuclear testing largely ceased after the 1990s, its political, environmental, and public-health consequences persist today. The international community now strongly condemns such tests. Yet for nearly two decades, from 1945 to 1963, nuclear testing was routine as nations competed for global influence.

The peak of testing during the Cold War

Nuclear testing accelerated sharply during the Cold War. The Arms Control Association reports that 1962 remains the record year, with 178 tests conducted—97 percent of them by the United States and the Soviet Union. The United Kingdom performed two tests that year, and France conducted one.

The same year also marked a critical turning point. The Cuban Missile Crisis brought the United States and the USSR to the brink of nuclear conflict. Growing public protests against the arms race, coupled with increasing awareness of testing’s health risks, began to shift global opinion.

A landmark 1961 study published in the journal Science examined baby teeth collected in St. Louis for strontium-90, a radioactive isotope produced by nuclear explosions and readily absorbed by children. The research revealed that strontium-90 levels were 50 percent higher in children born in the 1960s than in those born in the 1950s, even though St. Louis lay hundreds of miles from the Nevada test sites.

The findings sparked widespread public alarm and helped persuade the United States to sign the Limited Nuclear Test Ban Treaty in 1963, noted Tilman Ruff, former co-president of International Physicians for the Prevention of Nuclear War.

The shift toward underground testing

Less than a year later, the Limited Test Ban Treaty was presented to the United Nations and widely adopted. It banned nuclear explosions in the atmosphere, outer space, and underwater—environments where fallout spreads far more widely than in underground tests.

“By 1963, nearly two decades of bomb testing had poisoned the air, land, and water with hundreds of radioisotopes,” wrote Robert Alvarez of the Bulletin of the Atomic Scientists.

The 1954 Castle Bravo test illustrated the dangers vividly. Unexpected wind patterns and higher-than-anticipated yields exposed residents of the Marshall Islands to near-lethal radiation doses—the highest ever recorded after a single test. “The Rongelap Atoll in the Marshall Islands remains a radiological hazard because of life-threatening fallout from the 1954 Bravo test,” Alvarez added.

President John F. Kennedy was among the world leaders who signed the Limited Test Ban Treaty in 1963.
In total, 108 countries, including the United States and the Soviet Union, endorsed the treaty, ushering in a gradual era of disarmament. Nevertheless, hundreds of tests continued underground for decades. Nations such as China, India, Pakistan, and North Korea later began their own testing programs, despite the 1968 Non-Proliferation Treaty’s goal of curbing the spread of nuclear weapons.

The Comprehensive Nuclear-Test-Ban Treaty era

It was not until the Comprehensive Nuclear-Test-Ban Treaty (CTBT) was opened for signature in 1996 that testing effectively halted. Although the treaty has not yet entered into force, it has been signed by 187 countries.

The CTBT’s International Monitoring System, established in 1996, uses 321 stations equipped with seismic, hydroacoustic, infrasound, and radionuclide technologies to detect nuclear explosions anywhere on Earth. This network makes clandestine testing extremely difficult.

The most recent nuclear test occurred in 2017, when North Korea—which has not signed the CTBT—detonated a device estimated at 140 kilotons, roughly eight times more powerful than the Hiroshima bomb. As of 2026, no further nuclear tests have been recorded.

Long-term effects on health and the environment

“The concern and protests of people worldwide about radioactive fallout from nuclear testing have played a major role” in ending testing programs, Ruff observed. A 2006 study projected that fallout from U.S. tests in the 1950s and 1960s would ultimately cause approximately 22,000 additional radiation-related cancers and 1,800 additional deaths from radiation-related leukemia in the United States.

“For people in the immediate vicinity and downwind of nuclear test explosions, nuclear testing has had profound and long-term effects on their health and communities,” Ruff stated.

While the United States conducted many tests in Nevada, New Mexico, and Colorado, its largest detonations took place in the Marshall Islands. Between 1946 and 1958, the islands experienced “the equivalent of 1.6 Hiroshima bombs each day over the twelve years of the tests,” according to the International Review of the Red Cross. Beyond immediate health impacts, testing produced lasting social consequences, including displacement, loss of traditional lands, and economic hardship.

Day-to-day radiation levels across the United States have nevertheless declined sharply since atmospheric testing ended, the Environmental Protection Agency reports.

Could nuclear testing resume?

Nine countries currently possess nuclear weapons: China, France, India, Israel, North Korea, Pakistan, Russia, the United Kingdom, and the United States. Together they hold approximately 13,000 warheads.

North Korea’s 2017 test, combined with renewed missile activity in 2026, has once again raised regional tensions. For the first time, South Korea has openly discussed the possibility of developing its own nuclear deterrent.

Any decision by South Korea or another nuclear-armed state to resume testing would likely trigger similar moves by others. “Resumption of nuclear testing would be an extremely provocative and backwards step for the prospects of peace,” Ruff concluded.

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