U.S. officials and others who track the nuclear capabilities and internal politics of North Korea say they don't see any indications that Pyongyang is planning an imminent nuclear test, but they caution that after the embarrassment of Friday's failed rocket launch it could move provocatively and quickly to do so.

"We consider it at any time a possibility," said one U.S. official who follows North Korea and who briefed NBC News on condition of anonymity. "Might kind of ruin the party or enhance it", he added, referring to Sunday's celebration of North Korean founder Kim il-Sung's 100th birthday.

-- Reported by Robert Windrem, NBC News senior investigative correspondent