U.S. Warns North Korea Against Nuclear Test

WASHINGTON, May 6 - The White House warned North Korea on Friday that conducting a nuclear test would be "a provocative act," and Japan's foreign minister raised the possibility of requesting United Nations sanctions against the North.

The White House statement came a day after The New York Times reported growing concern among administration officials and several intelligence agencies about signs that North Korea might conduct its first nuclear test at a site near Kilju in the northeast.

Several officials confirmed those reports on Friday, and two officials with access to the information said satellites were also watching the construction of some platforms and crates hundreds of miles from the possible test site, near a nuclear reactor at Yongbyon.

The construction there may suggest that preparations are being made to remove spent nuclear fuel rods from the reactor, which was turned off more than a month ago. "It's still something of a mystery," said one of the officials with access to the report. "It's not clear if this construction is related to the rods or not."

If the rods are reprocessed, they could yield enough plutonium for a couple of new nuclear weapons, officials said. But officials have not ruled out the possibility that the reactor was shut for maintenance or as part of a ruse by the North to heighten concern that it is proceeding full steam with its nuclear program.

A few intelligence officials urged caution in interpreting the satellite evidence. While they acknowledge finding signs of continued activity near tunnels in the Kilju area, there is clearly some disagreement among intelligence agencies about whether the latest evidence indicates a drive toward a test.

"What worries us most is that there is a progression of openness among the North Koreans about their nuclear capabilities," said one senior administration official who has been studying the evidence. "They have unfolded new phases of specificity about what they can do, and they seem to have been on a long-term path of ending the ambiguity about their capability."