Nuclear weapons testing: Under project Smiling Buddha, India successfully detonates its first nuclear weapon becoming the sixth nation to do so.

Nuclear weapons tests are experiments carried out to determine the performance of nuclear weapons and the effects of their explosion. Over 2,000 nuclear weapons tests have been carried out since 1945. Nuclear testing is a sensitive political issue. Governments have often performed tests to signal strength. Because of their destruction and fallout, testing has seen opposition by civilians as well as governments, with international bans having been agreed on. Thousands of tests have been performed, with most in the second half of the 20th century.

Smiling Buddha was the code name of India's first successful nuclear weapon test on 18 May 1974. The nuclear fission bomb was detonated in the Pokhran Test Range of the Indian Army in Rajasthan. As per the United States military intelligence, the operation was named as Happy Krishna. The Indian Ministry of External Affairs (MEA) described the test as a peaceful nuclear explosion.

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either nuclear fission or a combination of fission and nuclear fusion reactions, producing a nuclear explosion. Both bomb types release large quantities of energy from relatively small amounts of matter.

India possesses nuclear weapons and previously developed chemical weapons. Although India has not released any official statements about the size of its nuclear arsenal, recent estimates suggest that India has 180 nuclear weapons. India has conducted nuclear weapons tests in a pair of series namely Pokhran I and Pokhran II.