On 2 December 2009, the 64th session of the United Nations General Assembly declared 29 August the International Day against Nuclear Tests by unanimously adopting resolution 64/35. 

The resolution calls for increasing awareness and education “about the effects of nuclear weapon test explosions or any other nuclear explosions and the need for their cessation as one of the means of achieving the goal of a nuclear-weapon-free world.” 
It was initiated by the Republic of Kazakhstan, together with a large number of sponsors and cosponsors with a view to commemorating the closure of the Semipalatinsk Nuclear Test site on 29 August 1991.

United States Army had conducted the first nuclear test, called Trinity, in a desert site of New Mexico on July 16, 1945. This test empowered United States to drop atom bombs on Hiroshima and Nagasaki in August 1945. This event resulted into an estimated 200,000 casualties while the survivors suffered from cancers due to radiation. Nuclear tests by USA and USSR led to the Cold War, that continued till 1991. About 2000 nuclear test explosions were conducted in between 1945 and 1996.

The main mechanism for eradicating nuclear weapons testing is the Comprehensive Nuclear-Test-Ban Treaty (CTBT). It was adopted by the United Nations General Assembly on 10 September 1996. To date, 185 countries have signed the treaty and 170 have ratified it. For the Treaty to enter into Force, it must be ratified by those States with significant nuclear capabilities.