U.S. Secretary of State Colin Powell has previously said North Korea might have "one or two nuclear weapons." But whether Pyongyang had the technology to miniaturize warheads was unclear.
However, a senior official in the Japanese government told the Japan Times Friday that several U.S. officials told Tokyo North Korea does have this capacity.
A senior aide to Prime Minister Junichiro Koizumi told the Japan Times that confirming the intelligence would be difficult unless North Korea conducts a nuclear weapons test.
Without ruling out the possibility that Pyongyang has nuclear warheads, Chief Cabinet Secretary Yasuo Fukuda said "there is nothing we can say for sure at this point in time."