The United States is exploring the development of a 'space-bomber' which could destroy targets on the other side of the world within 30 minutes.
As part of a weapons modernisation strategy personally directed by Defence Secretary Donald Rumsfeld, the Pentagon is drawing up plans for a 'sub-orbital vehicle' launched like a spacecraft, which Rumsfeld describes as 'valuable for conducting rapid global strikes'. The craft - which would set the scene for a new generation of stratospheric warfare - would be able to drop precision bombs from a height of 60 miles, flying at 15 times the speed and 10 times the height of America's current bomber fleet. It is unclear whether it would be manned.

Plans for the weapon appear to undermine claims that President George Bush's controversial Missile Defence Screen - dubbed 'Son of Star Wars' - is purely defensive.

The new plane could be developed quickly by adapting shelved research for Ronald Reagan's 'Star Wars' together with plans for a reusable spacecraft called the X-33 Venture Star, under development by Nasa and Lockheed Martin.

It would drop bombs from such a height that they would act as 'bunker busters', penetrating deep into underground silos without explosive warheads and causing massive pre-emptive damage on the ground within minutes of the start of a conflict - indicating a clear intention to take out enemy missiles before they have the capacity to launch. It would also be out of reach of conventional air defence systems.

The bomber could return to base in the US within 90 minutes from any point on the globe. In 1999 it took US bombers in Kosovo 24 hours to return to base in Missouri.

The development of the bomber - details of which have been obtained by the Los Angeles Times - has keen supporters, including the man tipped to be nominated by Rumsfeld as chairman of the Joint Chiefs of Staff, Air Force General Ralph Eberhardt, commander of Space Command.

Pentagon spokesman Admiral Craig Quigley is also optimistic, saying 'the military couldn't get anything [to a war zone] faster than this. It could be useful in any number of scenarios'.

But the plan also touches many raw nerves, most obviously among those who object to the militarisation of space, which Democrat Senate leader Tom Daschle calls 'the single dumbest thing I've heard from this administration'. The project's supporters deny that the craft marks a move to militarise space, saying that its targets would be on Earth and that it would not make a full orbit.

Last week the Pentagon announced its intention to test a space-based laser weapon, capable of zapping incoming missiles, as early as 2005 at a cost of $110 million. The test would signal a return to the heart of Reagan's Strategic Defence Initiative - the so-called 'Star Wars' - of the early 1980s and constitute a clear and offensive violation of the 1972 Anti Ballistic Missile Treaty with Russia.

And, The Observer has learnt, US embassies have been instructed to inform host governments that the administration intends to test not just land-based missile interceptors, as it did two weekends ago, but 'other technologies and basing modes' for such weapons.

As with many such projects, such as the Stealth bomber, the new craft could bypass a Congressional veto by being included in the secret 'black budget' of undeclared defence spending.

Dan Plesch, director of the British American Security Information Council, said the development revealed that America was engaged in military 'anarchism' and was seeking to dominate space militarily before China or Russia were able to do so.

'They are now engaged in a grossly militarised foreign policy which seems to be their only reaction to global politics,' he said.