NORTH Korea may have the bomb, but it hasn't perfected ways to put one onto a missile that could strike faraway enemies.

This is why Pyongyang's announcement that it will launch a satellite on a long-range rocket next month is drawing so much attention: Washington says North Korea uses these launches as cover for testing missile systems for nuclear weapons that could target Alaska and beyond.

And "beyond", according to Obama Administration senior official Kurt Campbell, could mean Australia.

Although North Korea isn't on the official agenda of next week's Nuclear Security Summit in the South Korean capital, the launch will be a major point of discussion when President Barack Obama and other world leaders gather in Seoul.

North Korea has spent decades trying to perfect a multistage, long-range rocket.

Next month's launch - set to happen around the April 15 centennial of the birth of founder Kim Il Sung - would be the fourth of its kind since 1998, when Pyongyang sent a long-range rocket hurtling over Japan.

The rocket is set to fire from a new site on the North's west coast, according to GeoEye and Google Earth satellite imagery posted by Tim Brown, an analyst for GlobalSecurity.org.

So far, Pyongyang can only deliver a nuclear bomb by boat, by van or by airplane - not by missile.

The new rocket will probably have better boosters and engines — and might even succeed in putting a satellite into space if it contains one, South Korean rocket scientist Sohn Young-hwan says.

North Korea may have loaded the rocket's third stage with more fuel to increase capability, another missile expert, David Wright told Associated Press, part of improvements that "would translate to greater range if that technology was used to build a long-range ballistic missile".

Yesterday, Mr Campbell delivered a blunt warning to the Foreign Affairs Minister Bob Carr, in Sydney.

The Sydney Morning Herald reports Dr Campbell, the assistant secretary of state for East Asia and the Pacific said: "If the missile test proceeds as North Korea has indicated, our judgment is that it will impact in an area roughly between Australia, Indonesia and the Philippines."

"We have never seen this trajectory before. We have weighed into each of these countries and asked them to make clear that such a test is provocative and this plan should be discontinued."

After the meting, Mr Carr told the Herald: "The North Korean nuclear and long-range missile plans represent a real and credible threat to the security of the region and to Australia."

Governments and experts are worried that a new rocket launch will spur a chain of events that will mirror 2009, resulting in a breakdown of diplomacy, another nuclear test and soaring tensions, threats and bloodshed.

The United States has warned the launch would jeopardize a diplomatic deal settled last month that would ship U.S. food aid to the impoverished North in exchange for a moratorium on missile and nuclear tests, as well as a suspension of nuclear work at Yongbyon.