WASHINGTON -- China set off the largest underground nuclear test it has ever conducted, the State Department said yesterday. The explosion was thought to have a yield of about 1 megaton, equivalent to a million tons of TNT.
The explosion was carried out in the desert wastelands of Xinjiang province in northwestern China -- site of the nation's Lop Nur nuclear test grounds. In Hong Kong, scientists initially thought they were registering an earthquake.
The test had 70 times the explosive power of the atomic bomb dropped on Hiroshima, and exceeded the 150-kiloton limit observed by Washington and Moscow under a 1990 treaty, scientists said.
"This suggests that the Chinese must be trying to develop large-yield, offensive nuclear warheads for long-range missiles," said Gary Milhollin, director of the Wisconsin Project on Nuclear Arms Control. "This is a city-buster."
But he emphasized that China was still no threat to the United States in the development of intercontinental ballistic missiles.
The Bush administration said it regretted Beijing's action and urged restraint.
There also were sharp condemnations of China in Congress. Legislators from both major parties have been critical of what they see as an unacceptably conciliatory policy toward China by President Bush.
The Chinese test was only one-fifth as powerful as the largest underground test by the United States, a 5-megaton blast in Alaska on Nov. 6, 1971, the most powerful underground nuclear explosion on record. A megaton is 1,000 kilotons.
The largest underground test by the Soviet Union was a 2.8- to 4-megaton blast on Oct. 27, 1973, a year before Moscow and Washington signed a treaty limiting the size of those explosions to 150 kilotons.
The Chinese test comes on the heels of persistent reports that Beijing is selling missile technology to Middle Eastern nations, and at a time when Beijing is harassing Western reporters and rejecting all criticism of its human-rights record.
"We regret that the Chinese have conducted this test and that they are not demonstrating the same restraint as shown by Russia, ourselves, or the other nuclear weapons states," the State Department spokesman, Richard A. Boucher, said yesterday.
Sen. Alan Cranston, a California Democrat who is chairman of the Senate Foreign Relations subcommittee on East Asia, called China a "renegade nation."