PLAYING the high-risk diplomatic poker that has been a constant feature of his term in office, President Kim Jong-il of North Korea is raising the stakes once more with the threatened test firing of a long-range Taepodong-2 ballistic missile.

Although there is no international law that prevents North Korea from launching a missile of this kind, the North Koreans claim they are using it as part of their space research programme, Japan has claimed it will constitute an act of aggression that breaks UN sanctions.

If the test goes ahead as planned later this week, Japanese air and sea defence batteries have been ordered to attempt to shoot it down - the trajectory of the first and second stages will take the missile over the Japanese homeland.

"We will do our best to handle any flying object from North Korea in order to ensure the Japanese people's safety and security," said defence minister Yasukazu Hamada yesterday.

"A satellite or a missile - we are displeased with anything that is going to fly over our land, and such an action must be stopped."

At the heart of the matter is the missile's payload. North Korean officials claim it will be carrying a satellite for peaceful scientific purposes but Japanese defence officials are convinced the North Koreans have designed the missile to carry a warhead.

By Japan's calculations, this would bring Alaska within range and yesterday the tension was notched up further when US chairman of the Joint Chiefs of Staff, admiral Michael Mullen, claimed the enhanced Taepodong-2 would be capable of hitting Hawaii, the base of the US Pacific fleet.

Officially, the missile has a range of 6700 kilometres (4163 miles). Whatever the reason for the test firing, the secretive North Korean leader has ramped up tensions in the region bounded by the Sea of Japan and East China Sea.

Two Japanese Aegis-class destroyers have been deployed, together with US and South Korean warships, and on Japan's northern coast, Patriot PAC-3 anti-missile batteries are on high alert with orders to shoot down the rogue missile or any fragments as it breaks up. In reply, the North Koreans insist this would be provocative and an act of war, a riposte that forced Japan's foreign minister Hirofumi Nakasone to curb expectations. "Our country has never done this before," he admitted yesterday. "And we don't know how or where it may come flying."

A more workable solution would see North Korea being reported to the UN for breaking the terms of Resolution 1718, which imposed arms controls on the country and bans it from testing new weapons of war. However, Japanese and US diplomats have conceded any initiative would not prevent North Korea from pushing ahead with the exercise and could even lead it to boycott the international talks aimed at controlling the country's nuclear programme.

As the war of words continues, diplomats in Tokyo and Washington are attempting to get behind the posturing to discover the reasons behind Pyongyang's provocative stance.

Although not much is known about Kim's health, following a reported stroke last year, and with questions remaining about his hold on power, it would be in his nature to offer an early challenge to US President Barack Obama. By test firing a ballistic missile, Kim would send a message to the US and its principal allies in the region that North Korea still carries some clout.

From a regional perspective, Kim will also be keen to get the Taepodong-2 off the ground before South Korea tests a similar missile in July. However, it is unlikely North Korean scientists are close to producing a nuclear warhead.

Not only has the nation closed its main nuclear plant at Yongbyon in return for economic aid, but it also lacks the technology to miniaturise a nuclear warhead to use on a relatively unsophisticated ballistic missile. It is also doubtful if the North Koreans possess the necessary guidance systems.

"Let's be honest and admit the North Korean missile presents no clear and present danger to the Japanese people," said a US diplomatic source. "Throughout the six-nation talks on curbing their nuclear ambitions they've played a long game and this is simply their latest pitch. They think time is on their side."

Yesterday, international security publication Jane's Defence Weekly said preparations for a test firing of the missile were ahead of schedule. It is almost three years since North Korea tried a similar test, when the missile exploded seconds after take-off.