The official, who spoke on condition of anonymity, refused to characterize the talks as succeeding or failing to make progress in addressing concerns about North Korea's export and development of missiles. ``I wouldn't want to try to measure this on the progress meter,'' the official said. ``It's up to the North Korean side now to go back to Pyongyang and think about wh at we had to say.''

``It's hard to anticipate what progress, if any, will be possible in the next round,'' he said, adding that the talks would resume before the end of the year. ``The choice really is up to them.''

If North Korea engages ``in certain troublesome activities, this would have very negative consequences,'' he said, noting that if Pyongyang halted its missile programme Washington would likely ease economicsanctions.

Sustained missile activities ``will destroy support in the United States and elsewhere ... for cooperative activities,'' he said, alluding partly to anger among US legislators at a policy they view as far too indulgent toward North Korea.

The official ruled out North Korea's longstanding request for $ 500 million annual compensation in exchange for which the starving Stalinist country would a gree to halt its export of missile technology. ``We don't think that's appropriate,'' he said.