Page 5: Nuclear Testing: 1945-2009

Burgeoning nuclear arsenals

The world’s nuclear arsenals ballooned throughout the Cold War, from slightly more than 3,000 weapons in 1955 to over 37,000 weapons by 1965 (United States 31,000 and the Soviet Union 6,000), to 47,000 by 1975 (United States 27,000 and Soviet Union 20,000), and over 60,000 in the late 1980s (United States 23,000 and the Soviet Union 39,000).

According to the Nuclear Threat Initiative, Israel initiated a nuclear programme in the 1950s, and had completed the R&D phase of its nuclear weapon programme in 1966, although it has not, to public knowledge, tested such a weapon. Israel has adopted a so-called “nuclear ambiguity policy”, neither confirming nor denying its nuclear status. It is not a party to the 1968 Non-Proliferation Treaty, and it has signed but not ratified the CTBT. For more information about Israel and the CTBT, click here.

Officially, India became the sixth nation to develop nuclear weapons, conducting the "Smiling Buddah" nuclear test on 18 May 1974, declared as a "peaceful" nuclear explosion.

In 1982, one additional nation, South Africa, acquired nuclear weapons, according to the Monterey Institute’s Center on Non-Proliferation Studies. To public knowledge, South Africa did not conduct any nuclear tests (see also the Vela incident). Less than ten years later, with the anticipated transition to a majority-elected government, South Africa dismantled all of its nuclear weapons, the only nation to date that voluntarily relinquished the nuclear arms under its complete control. The dismantling was completed in 1991. The same year, South Africa acceded to the 1968 Non-Proliferation Treaty as a non-nuclear weapon State. It voted overwhelmingly to end apartheid on 18 March 1992.

Underground nuclear testing was banned by the 1996 Comprehensive Nuclear-Test-Ban Treaty, which bans all nuclear explosions on Earth.

The world did not witness any significant decrease in nuclear testing activities and nuclear weapons acquisition among the nuclear weapon States until the early 1990s. The total number of  nuclear tests in the second half of the 1980s amounted to as many as 174.

But warmer relations between the Soviet Union and the United States from the mid-1980s prepared the way, as did the fall of the Berlin Wall in 1989 and the 1991 dissolution of the Soviet Union, which was superseded by the Russian Federation. Belarus, Kazakhstan and Ukraine who, together with Russia, had hosted the Soviet nuclear arsenal, became non-nuclear weapon States under the Non-proliferation Treaty. The USSR's main test site, Semipalatinsk in Kazakhstan, was closed in 1991.