The detonation of three underground nuclear devices in India's western desert is sending shockwaves around the world.
The tests - the first there since 1974 - have shaken post-cold-war global arms control efforts and may threaten the stability of Asia.
Authorized by India's new Hindu nationalist government, yesterday's blasts could accelerate a debilitating regional arms race. Pakistan, which has fought India three times since 1948 and has its own clandestine nuclear program, may feel compelled to test an atomic weapon for the first time, experts warn.
The Indian explosions could also reignite tensions between India and communist China, one of the world's five declared nuclear-weapons powers. The two clashed in 1962 over a still-unresolved border dispute. Last week India's defense minister called China the main threat to Indian security.
A surge in regional tensions could prompt other nations in Asia to boost military spending at a time when they can ill-afford it because of the financial crisis that is rocking their economies.
"The significance of this development really cannot be overstated," says John Medalia, a congressional arms-control expert. "All of a sudden, India has tossed a match onto a tank of gasoline."
Beyond the regional impact, the Indian detonations could undermine international efforts to rid the world of nuclear weapons by further complicating implementation of a 1996 global treaty to ban atomic test explosions.
China, experts say, could reconsider its membership in the Comprehensive Test Ban Treaty (CTBT), while in the United States, the blasts could bolster conservative Republican senators determined to block ratification of the pact, one of President Clinton's top foreign-policy priorities.
"This [the Indian tests] runs counter to the effort the international community is making to promulgate a comprehensive ban on such testing," asserts White House spokesman Mike McCurry.
The explosions hold serious implications for US relations with India, the world's largest democracy. The Clinton administration is required by law now to impose economic sanctions on New Delhi, including a cutoff of all US bank loans, unless Congress objects. Such a cutoff could devastate the Indian economy, which experts say is already overextended and undercapitalized.
Furthermore, Mr. Clinton may also have to reconsider a visit to India scheduled for November. "It's impossible to tell what the impact is on the trip at this point," says Mr. McCurry.
The tests stunned world powers even though the Hindu nationalist Bharatiya Janata Party-led (BJP) coalition government had made it clear that it intended to push a nuclear-weapons policy in a bid to make India a major global military power. The move is also designed to strengthen domestic support for the BJP's fragile coalition, which was formed in March, analysts say.
The test blasts confirmed what was long suspected: India has been aggressively pursuing a clandestine atomic-weapons-development program since the 1974 detonation of a device that it has consistently contended was for peaceful purposes only.
"These tests have established that India has a proven capability for a weaponized nuclear program," Brijesh Mishra, an aide to Indian Prime Minister Atal Behari Vajpayee, said in New Delhi after Mr. Vajpayee announced the explosions at a news conference.
Vajpayee said three devices were detonated at the Pokhara test facility in the western desert state of Rajasthan. They included a thermonuclear bomb, a much more complex and powerful device than that exploded in 1974.
Experts say the tests appeared aimed at confirming India's ability to build powerful nuclear payloads small enough to carry aboard missiles, including the Prithvi, an intermediate-range rocket that can reach virtually every city in Pakistan. India is also developing the Agni, a longer range rocket that could deliver warheads across much of Asia, including China and parts of the Middle East.
"These tests were devised to increase the yield-to-weight ratio drastically so they can put warheads on missiles," asserts Henry Sokolski, a former Pentagon official and director of the Non-Proliferation Policy Education Center in Washington.
India launched its clandestine nuclear-weapons program shortly after China conducted its first nuclear test blast in late 1964. India is believed to have extracted from its nuclear reactors enough plutonium to make some 80 bombs. Experts say it can also enrich uranium for use in atomic weapons.
Pakistan, a largely Muslim nation, appeared to confirm fears of a new arms race, with Foreign Minister Gohar Ayub Khan saying in Islamabad that the country "reserves the right to take appropriate measures for its security."
Islamabad has been pursuing a secret nuclear-weapons program, allegedly with Chinese assistance and thefts of Western technology, since its defeat in the 1971 Indo-Pakistan war. Experts believe it can quickly assemble as many as 25 nuclear weapons using uranium from an unsafeguarded reactor.
Pakistan has been furiously countering India's missile development programs with those of its own. Last month, it tested a rocket capable of delivering a 700-kilogram warhead to a distance of 1,200 kilometers.
India and Pakistan, which are locked in a dispute over the northern Kashmir region, refused to sign the CTBT after it was approved by the United Nations and signed in 1996 by 149 nations.
The treaty, however, cannot go into effect until all 44 nations with nuclear reactors, including India and Pakistan, sign and ratify it. A special conference is to be held in September 1999 by those countries that meet the criteria to decide how to proceed with its implementation.
In the US, conservative Republicans led by Senate Foreign Relations Committee Chairman Jesse Helms (R) of North Carolina oppose ratification of the treaty and have dragged their heels on holding hearings on it.
Opponents argue the pact will undermine US national security by prohibiting periodic underground test explosions that they say are needed to ensure the reliability and safety of the American nuclear arsenal.
Some analysts say that opponents will seize on the Indian tests to obstruct ratification of the treaty.
"This could further strengthen Senator Helms's arguments for not moving quickly on the CTBT," says a congressional source.
The Clinton administration and the military services, however, insist that the reliability and safety of the stockpile can be ensured through a 10-year, $45 billion program that employs computer simulation and other advanced technologies.