``It would be the greatest intelligence failure in the history of the United States,'' a western military analyst here said.

If Pyongyang's announcement that it launched a satellite which is now playing hymns in space is verified, ``then we are all in trouble as it's unthinkable that the US surveillance should have missed such an event.'' If the launch proved not to be that of a medium-range ballistic missile as reported by the US, Japanese and South Korean intelligence services, it would be highly embarrassing and raise fundamental issues, he said.

``If they did miss its launch and development, then that raises all sorts of questions about what else they might have missed and in fact what good do the 100,000 men in the region do if they have no idea of what's going on there.''

TheUS military has around 60,000 troops in Japan and 37,000 in South Korea to guard against any attack from the unpredictable Stalinist North and to monitor its movements. North Korea at the weekend scoffed at its traditional foes who were alarmed by the revelation that Pyongyang had launched a missile, boasting lavishly of its first satellite launch as the world scrambled to verify the stunning claim.

``Some people suspected it to be a ballistic missile launching test, while some expressed apprehensions, and described it as a serious event,'' its Central Radio said in a broadcast here. The US, which boasts of having the world's most sophisticated satellites and surveillance techniques, is believed to supply surveillance information on North Korea to its allies in both South Korea and Japan.

A failure to notice that famine-hit and impoverished North Korea had made a giant leap into satellite development and launch-technology would be a huge step and would raise questions about what other secret advances ithas achieved.

There are fears that Pyongyang has a nuclear weapons programme, frozen after a last-minute deal with the United States in 1994, which diplomats said averted the threat of war in the region. But diplomats and analysts here said the task of watching and interpreting events in the isolated hermit state is one of the world's toughest intelligence jobs. ``Nobody has known for decades what they are thinking, what their strategy is, or, how they reason,'' an avid North Korea watcher said.

In Washington, surprised intelligence officials said they could not rule out that North Korea placed an object in orbit, but said there was no doubt the projectile fired over Japan on Monday was a two-stage Taepo-Dong 1. But Russia's news agency Itar-Tass reported that Moscow's space observation centre had spotted the alleged satellite.