U.S. intelligence agencies have detected activity at facilities in North Korea indicating Pyongyang may be preparing to conduct its first nuclear test in the near future, according to U.S. officials.
The Bush administration has made a private diplomatic appeal to the Chinese government to use its influence with the North Koreans to head off any test.
A North Korean nuclear test would bring the communist state into the exclusive club of nations that are declared nuclear powers.
Any test also would increase tensions in the region and possibly spur Japan or other nations to seek their own nuclear weapons.
The suspected test-related activity was detected by U.S. spy satellites in the past several days, said officials who spoke on the condition of anonymity. It was reported by the National Geospatial-Intelligence Agency, which is in charge of analyzing satellite photographs.
North Korea is believed to have underground facilities for its nuclear activities at several locations across the country.
One U.S. official familiar with the issue said the intelligence on test preparations is “ambiguous.”
Other officials said the intelligence included indications related to testing activity that for other nuclear powers normally includes a site where a device is placed in a deep hole and the monitoring equipment is deployed nearby.
Little is known about North Korea’s covert nuclear efforts, which triggered a crisis in October 2002 that led to the current stalled talks on the issue.
North Korea’s known nuclear facilities include the Yongbyon complex, where a reactor recently was shut down in what officials think could be preparation for additional reprocessing of spent fuel into bomb-making material.
A second official said North Korea could be at the point of testing a nuclear device.
North Korea is believed to have enough nuclear fuel for one or two weapons and could have enough seed material for up to eight bombs, according to U.S. officials.
The second official said North Korea in recent weeks has declared openly that it has nuclear weapons and that “a test would be the next step.”
White House National Security Council spokesman Frederick Jones declined to comment on the North Korean activity or the appeal to China. Mr. Jones said he could not discuss “our diplomatic conversations or intelligence matters.”
In September, U.S. intelligence agencies detected a mushroom cloud in a remote region near North Korea’s border with China that at first was thought to have been the result of a possible nuclear test.
It later was found to have been an unusual cloud formation, and no radiation was ever detected near the cloud from the U.S. sensors that monitor North Korea.
Those sensors include special “sniffer” equipment that can detect nuclear material in the atmosphere.
A CIA report made public in November said that North Korea threatened to “demonstrate” its nuclear weapons or to “transfer” weapons abroad.
The threat was made at the April 2003 talks and again in August 2003, the CIA report said.
Administration officials said the threat was first made by North Korean negotiator Li Gun during a meeting with James Kelly, assistant secretary of state for East Asia, during a closed-door meeting in Beijing.
Mr. Li told Mr. Kelly that the communist state would “export nuclear weapons, add to its current arsenal or test a nuclear device,” according to an official familiar with the exchange.
Sharon Behn contributed to this report.