China Detonates Nuclear Blast but Vows to Join Ban

China detonated an underground nuclear explosion Saturday but promised it will halt such tests after one more blast sometime this year.

Monitors at the Australian Geological Survey Organization in Canberra said they detected an explosion with the yield of a 20- to 80-kiloton bomb at China’s Lop Nor test site, located in a remote desert in western China. The blast, China’s 44th test since 1964, had the intensity of a 5.7-magnitude earthquake.

The test came on the heels of China’s announcement Thursday that it will join a global moratorium on nuclear testing, giving up a long-held demand to conduct “peaceful” nuclear explosions even after the Comprehensive Test Ban Treaty is in place. The issue had been an obstacle to the signing of the pact, which is due for ratification by the U.N. General Assembly in September.

Despite the Chinese promise to halt nuclear tests, Saturday’s blast sparked world condemnation. The United States joined Australia, Japan and Germany in deploring the explosion.

“The United States deeply regrets this action,” White House Press Secretary Mike McCurry said in a statement. “We urge China to refrain from further nuclear tests and to join in a global moratorium.”

A boat owned by the environmental group Greenpeace set sail for Shanghai from Manila on Saturday evening to protest China’s continued tests. The MV Greenpeace, whose launch was delayed because of repairs, is scheduled to reach Shanghai on Wednesday, although Chinese officials have denied it permission to dock.

“Today’s test undermines any notion of progress made at the conference,” Greenpeace spokesman Damon Moglen said in Hong Kong.

Past tests have also drawn international criticism and sanctions, with the reaction often heightened by the blasts’ timing. Japan froze grant aid to China after a test in August that came days after the 50th anniversaries of the Hiroshima and Nagasaki atomic bombings. Tokyo officials said Japan will not impose further economic sanctions this time.

China’s announcement Thursday on the test moratorium, which was made at an international conference on disarmament, came with strings attached: The concession was made on the condition that inspection and verification procedures are modified and that the agreement is reviewed in 10 years.

The changes in inspection procedures would make it harder to monitor suspicious nuclear activity, verification specialists say.

Chinese officials said Saturday that just one more explosion is scheduled. “Before September this year, China will conduct another nuclear test to ensure the safety of its nuclear weapons,” China’s Foreign Ministry said in a statement. “After that, China will exercise a moratorium on nuclear testing.”