Pakistan then carried out its own tests, saying it had been forced to do so in the interests of national security.

This special report offers a guide to news stories on the subject, and the issues behind them.

India carries out tests

May 11: The news report confirming that India had conducted its first nuclear tests since 1974.
Outcry over India's nuclear tests

May 13: India conducts a second round in its planned series of five tests.
India detonates two more bombs

May 16: The Indian Prime Minister, Atal Behari Vajpayee, admits his country's nuclear weapons status.
India admits N-bomb capability

May 17: India's nuclear scientists disclose details of the latest nuclear tests and the new weapons they are working on.
India's nuclear blast bigger than Hiroshima

May 19: Indian authorities are to investigate allegations of radiation sickness among villagers living near the nuclear test site.
India to probe radiation claims

May 21: India announces a moratorium on further nuclear testing, saying the country's weapons are only for self defence.
End to India's nuclear tests

May 27: The Indian Prime Minister says India is ready to discuss a 'no-first-use' agreement on nuclear weapons.
India `committed to restraint'

May 31: The Indian Prime Minister calls for talks leading to a convention on nuclear weapons.
India calls for talks on nuclear weapons

Pakistan retaliates

May 16: As reports say that Pakistan's nuclear programme may be more advanced than India's, the Pakistani foreign minister warns that his country will almost certainly retaliate.
Pakistan poised to leapfrog India

May 28: Pakistan warns India of 'swift and massive retaliation' if India attacks its nuclear installations - and correspondents say a test looks imminent.
Pakistan warns of 'massive retaliation'

May 28: Pakistan explodes five underground nuclear devices.
Pakistan carries out nuclear tests

May 28: While Pakistan has been widely condemned abroad, the people at home are celebrating.
Pakistanis triumphant over n-tests

May 29: Unnamed US officials believe Pakistan may test again.
US warns Pakistan may test again

May 30: Pakistan carries out a further nuclear test.
Pakistan carries out another nuclear test

May 30: Pakistan says it is prepared to hold talks with other countries to find ways of promoting nuclear disarmament.
Pakistan calls for talks on disarmament

May 31:Pakistan's chief scientist talks of arming nuclear missiles.
Pakistan 'could make nuclear warheads within days'

International response

May 14: China joins international condemnation of the tests, accusing India of trying to control the region's politics.
China joins criticism of India

May 18: The United Nations Secretary-General, Kofi Annan, urges Pakistan not to test nuclear warheads and appeals to India to sign two nuclear weapons treaties.
UN appeal to stop arms race

May 26: The World Bank delays a decision on whether to approve more than $860m in loans to India, following the country's two series of nuclear tests earlier this month.
World bank delays big loans to India

May 28: The United States and Japan both announce sanctions against Pakistan, and other countries and international bodies condemn Pakistan's action.
World condemnation of Pakistan

May 28: The Indian prime minister says Pakistan's nuclear tests have vindicated India's decision to conduct its tests.
India says it is 'vindicated'

May 30: A further nuclear test by Pakistan is followed by international criticism.
Latest nuclear test condemned

May 31: Amid international criticism of Pakistan, the United Nations Security Council issues a statement deploring the latest explosions.
UN Anger at latest nuclear test

The response from the world's media

May 13: Indian public opinion swings behind the government and its decision to test nuclear weapons.
Indians swing behind tests

May 15: Mixed feelings in the Pakistani media on the question of whether the country should follow India and conduct its own nuclear tests.
Media divided over nuclear response

May 29: A press review of world reaction to Pakistan's nuclear tests
Nuclear tests dominate world headlines

Talking Points

We asked you whether India and Pakistan should have carried out nuclear tests.