[2] The Soviet Union was not informed officially of the Manhattan Project until Stalin was briefed at the Potsdam Conference on July 24, 1945, by U.S. President Harry S. Truman,[3][4] eight days after the first successful test of a nuclear weapon.

[5] A ring of spies operating within the Manhattan Project, (including Klaus Fuchs[6] and Theodore Hall) had kept Stalin well informed of American progress.

[10] In the years immediately after the Second World War, the United States had a monopoly on specific knowledge of and raw materials for nuclear weaponry.

American leaders hoped that their exclusive ownership of nuclear weapons would be enough to draw concessions from the Soviet Union, but this proved ineffective.

[citation needed] Just six months after the UN General Assembly, the United States conducted its first post-war nuclear tests — Operation Crossroads.

[13] Again, the Soviets surprised the world by exploding a deployable thermonuclear device in August 1953, although it was not a true multi-stage hydrogen bomb.

[citation needed] They were eventually evacuated, but most experienced radiation poisoning; one person was killed, a crew member on a Japanese fishing boat which was 90 miles (140 km) from the bomb test site when the explosion occurred.

[18] With both sides in the Cold War having nuclear capability, an arms race developed, with the Soviet Union attempting first to catch up and then to surpass the Americans.

While some, like General Douglas MacArthur, argued nuclear weapons should be used during the Korean War, both Truman and Eisenhower opposed the idea.

Aerial photography later revealed that the Soviets had been playing a sort of Potemkin village game with their bombers in their military parades, flying them in large circles, making it appear they had far more than they truly did.

In 1952, the United Kingdom became the third nation to test a nuclear weapon when it detonated an atomic bomb in Operation Hurricane[25] on October 3, 1952, which had a yield of 25 kilotons.

The Resolution-class ballistic missile submarines armed with the American-built Polaris missile provided the sea deterrent, while aircraft such as the Avro Vulcan, SEPECAT Jaguar, Panavia Tornado and several other Royal Air Force strike aircraft carrying the WE.177 gravity bomb provided the air deterrent.

The People's Republic of China became the fifth nuclear power on October 16, 1964, when it detonated a 25 kiloton uranium-235 bomb in a test codenamed 596[29] at Lop Nur.

While the U.S. military had been ordered to DEFCON 2, the theory of mutually assured destruction suggests that entry into nuclear war is an unlikely possibility.

Information that the U.S. had withdrawn their Jupiter Missiles from Turkey remained confidential for decades, causing the result of the negotiations between the two nations to appear to the world as a major U.S. victory.

It was felt by American and Soviet leaders that something had to be done to ease the significant tensions between these two countries, so on October 10, 1963, the Limited Test Ban Treaty (LTBT) was signed.

However, in light of the Soviet Union's invasion of Afghanistan in December 1979, the United States Senate never ratified the SALT II treaty.

[37] Simultaneously, however, Reagan initiated negotiations with Mikhail Gorbachev, ultimately resulting in the Strategic Arms Reduction Treaty on reducing nuclear stockpiles.

With the wave of revolutions sweeping across Eastern-Europe, the Soviet Union was unable to impose its will on its satellite states and so its sphere of influence slowly diminished.

[citation needed] Fewer new systems were developed, and both arsenals were reduced, although both countries maintain significant stocks of nuclear missiles.

[citation needed] Large amounts of money and resources – which would have been spent on developing nuclear weapons in the Soviet Union, had the arms race continued[citation needed] – were instead used for repairing the environmental damage produced by the nuclear arms race, and almost all former production sites are now major cleanup sites.

On 13 December 2001, George W. Bush gave Russia notice of the United States' withdrawal from the Anti-Ballistic Missile Treaty.

Russian President Vladimir Putin responded to the withdrawal by ordering a build-up of Russia's nuclear capabilities, designed to counterbalance U.S.

The next day, Trump reiterated his position to Morning Joe host Mika Brzezinski of MSNBC, stating: "Let it be an arms race.

"[43] In October 2018, the former Soviet leader Mikhail Gorbachev commented that U.S. withdrawal from the INF nuclear treaty is "not the work of a great mind" and that "a new arms race has been announced".

[44][45] In 2019, Russian Deputy Foreign Minister Sergey Ryabkov warned about the risk of nuclear war, as negative dynamics had been noticeable over the previous year.

Roughly 99% of the people in the US, Europe, Russia and China would starve to death if they did not die of something else sooner with 95% of the fatalities being in countries not initially involved.

[52] In July 2024, the Biden administration announced its intention to deploy long-range missiles in Germany starting in 2026 that could hit Russian territory within 10 minutes.

The nuclear competition started in 1974 with India detonating a device, codenamed Smiling Buddha, at the Pokhran region of the Rajasthan state.

Domestic pressure within Pakistan began to build and Prime Minister Nawaz Sharif ordered a test, detonating six nuclear weapons (Chagai-I and Chagai-II) in retaliation and to act as a deterrent.