North Korea may be preparing to launch a long-range ballistic missile that could reach parts of the United States, Japanese media reports said on Friday, but Japan's government said it did not believe a launch was imminent.
Quoting unidentified South Korean government officials, public broadcaster NHK said satellite pictures showed there have been signs since early this month around a site in north-eastern North Korea that pointed to a possible firing in the near future.
Analysts have said, though, that development of a multiple-stage version of a ballistic missile that can take payloads deep into the continental United States is years away.
Japan's top government spokesman, Shinzo Abe, said he could not comment on specific security issues, but added, "At the moment, we do not believe that a launch is imminent."
Askedf the situation posed a threat to Japan's national security, Prime Minister Junichiro Koizumi said: "Japan maintains its security through deterrence under the Japan-US security alliance and I believe North Korea knows that."
He added that he did not believe the situation was serious.
The latest reports come amid a deadlock in six-party talks aimed at dismantling North Korea's nuclear programmes, and ahead of a visit to China next week by the chief US negotiator to the talks that involve the two Koreas, the United States, Japan, Russia and host China.
North Korea has said in numerous official media reports that it is building a nuclear deterrent to counter US hostility. The United States believes that North Korea has one or two nuclear bombs and the ability to build more.
US officials said on Thursday that Washington was open to discussions with North Korea on a peace treaty at the same time as the six-party nuclear talks, but that Pyongyang must return to the negotiating table first.
North Korea has long demanded a peace treaty to replace the armistice that ended the 1950-53 Korean war.
Some experts detected in the US stance at least a slight change in emphasis designed to entice Pyongyang back to the table and keep Asian allies from blaming Washington for the moribund diplomacy.
NHK said the missile appeared to be a Taepodong-2, which previous reports have said has a range of more than 6,700 km (4,200 miles), making it capable of hitting Alaska with a light payload.
Quoting Japanese government sources, Japan's Kyodo news agency also said that a launch could be imminent and that the missile was probably a Taepodong-2.
However, a report in March by the California-based Centre for Non-proliferation Studies, a non-governmental organisation, said North Korea did not have an operational missile that could hit the continental United States.
That report said Pyongyang was working on a solid-fuel missile, Taepodong-X, with a range of up to 4,000 km (2,500 miles) that could hit Japan as well as US bases in Guam, but North Korea has yet to demonstrate its reliability through a test flight.
North Korea shocked the world in August 1998 when it fired a Taepodong missile that flew over Japan before splashing down in the Pacific Ocean.
NHK, quoting US government officials, said if the missile was a modified version of the Taepodong-2, it could have a range of 15,000 km (9,300 miles), which would cover all of the United States.
US officials have said the North is developing longer-range missiles that could hit the continental United States.