North Korea is preparing to test fire a long range missile capable of striking the United States, according to media reports in South Korea and Japan this morning.

The Yonhap News Agency in Seoul quoted South Korean officials who described satellite image showing a long cylindrical object being transported on a train through the North Korean countryside. The sinister object has been identified as a Taepodong-2, an intercontinental missile with a range of more than 4000 miles, capable of crossing the Pacific and striking targets in Hawaii or Alaska.

It is impossible to confirm independently reports from North Korea, one of the world’s most isolated and hardline dictatorships, where government of information is almost total. But the country is known to have an active missile programme, as well as nuclear warheads – although crucially it probably does not have the technology to mount a nuclear device on a long range missile.

The unnamed sources quoted by Yonhap said that any test launch was unlikely for at least a month or two. The train appeared to be heading from a missile factory in North Pyongan province in the country’s north-west to a newly constructed launch site on the west coast.

Pyongyang’s last long range missile launches in 2006 and 1998, from a base in the east, caused shock across the region, particularly in Japan, where there is a deep sense of vulnerability to North Korean attack. The apparent preparations for a launch, which are easily discernible by spy satellites, may be intended by the government as a way of asserting itself as it prepares to resume nuclear disarmament negotiations with the new U.S. government of Barack Obama.

The news comes just before the 67th birthday of the country’s “Dear Leader” Kim Jong Il -– a day which is sometimes celebrated with gestures regarded as proud national or military achievements.

North Korea bought its first Scud missiles during the 1960s from the Soviet Union and China. Over the years, scientists in North Korea enhanced the original Soviet technology, but all were inaccurate, mechanically unreliable, and had ranges of only a few hundred miles.

A breakthrough came with the development of the Nodong missile, with a range of up to 800 miles. It is still an inaccurate weapon, but it could potentially be used to carry nuclear or chemical warheads. This was the weapons said to have been purchased in blueprint form by Benazir Bhutto, then the Prime Minister of Pakistan, in 1993.

North Korea’s most shocking ballistic gesture came in 1998 when it test-fired a new three-stage long-range missile into the Pacific Ocean. The course of the so called Taepodong took it over the north coast of Japan; even more alarmingly, its range approached that of an intercontinental ballistic missile.

North Korea's Scuds are able to reach all of South Korea, its Nodongs could attack Japan, and the Taepodong 2, which is believed to be in development, has the potential to threaten even Australia.