WASHINGTON: The stunning image of a Navy missile streaking into outer space at 10,000 kph to obliterate an orbiting spy satellite boosts the credibility of missile-defence advocates. Yet questions remain whether that success could be duplicated against a surprise, real-world attack.

The idea, whether the target is an unarmed satellite or an enemy missile, is basically the same: fire a guided missile into the path of the moving target and smash it to bits by the force of impact. In theory, the collision could render harmless even a nuclear- or chemical-armed missile, an idea that evolved from President Ronald Reagan’s “star wars” programme of the 1980s.

In the case of the spy satellite, a Navy SM-3 missile launched from a cruiser in the Pacific not only hit the US satellite but apparently struck precisely where its operators had aimed: a titanium-encased tank of fuel that officials said could pose a health hazard to humans on re-entry.

Henry Cooper, who was the Pentagon’s “star wars” chief from 1990-93, said the outcome bodes well for the Navy and prospects for adding to its missile defence repertoire.

“It’s definitely a boost for the Navy program because everybody is made aware of the flexibility and perhaps even the reliability of programme,” Cooper said in a telephone interview.

It was the first time a US Navy missile interceptor had been used in an anti-satellite role.

It was not exactly a dry run for a missile defence test, but there are significant parallels. One is that neither mission against a satellite or a missile can be executed successfully without a network of space- and ground-based radars to track the target and to cue the intercepting missile. The satellite shoot-down offered a chance to coordinate all those missile defence-related pieces.

“The successful intercept is further validation of America’s sea-based missile defence capability,” said Rep. Duncan Hunter, the senior Republican on the House Armed Services Committee.

The satellite, deemed worthy of a shoot-down because of the slim possibility that its fuel tank could land in a populated area, was moving faster and travelling at a higher altitude than the missiles that the SM-3 had hit in controlled anti-missile tests. So it was a new challenge for the Navy missile.

“It did confirm the ability of the SM-3 to intercept at a higher elevation,” said Baker Spring, a specialist at the Heritage Foundation think tank and a long-time advocate of missile defences.

Raytheon, the maker of the SM-3, said the missile was put in an unexpected role.

“The missile was never designed to engage a satellite,” company spokesman David Albritton said.

A major problem in ballistic missile defence is that an opponent like China might equip a warhead with enough decoys and other countermeasures to “outsmart” and evade a US missile interceptor. Or it might launch a big enough volley of missiles to overcome a limited defensive system.

That is not an issue when shooting at satellites, which move in isolation on a relatively predictable path through space. Which helps explain why the United States has chosen not to field an arsenal of anti-satellite weapons: the risk of inviting retaliation against highly vulnerable US satellites, which are vital to national and economic security.

This is a particularly touchy issue with China, which drew strong US condemnation last year when it downed one of its own weather satellites, creating a large amount of space debris. Wednesday’s US shoot-down was timed to minimise the amount of debris that would remain outside the atmosphere. Space is increasingly a field of military competition between China and the US.

The Pentagon had shown decades ago that it could smash an orbiting satellite. This week’s strike showed that it could be done with an improvised array of missiles, radars and command systems that at times have failed to perform as advertised in tests against long-range ballistic missiles.

Rep. Ike Skelton, the Democratic chairman of the House Armed Services Committee, applauded the outcome of the satellite shoot-down but stressed that it should stand as a one-of-a-kind operation.

“This action should not be construed as standard US policy for dealing with problem satellites,” he said.

It is not the policy of the US government to field anti-satellite weapons. But some of the same technologies are at the heart of the Bush administration’s efforts to accelerate the development of a far-flung network that can reliably defend US and allied territory against ballistic missiles. The Bush administration has spent about $10 billion a year on missile defence in recent years.

At the Pentagon, Gen James Cartwright told reporters it would be wrong to think that the satellite shoot-down was done to demonstrate that the US military has an anti-satellite capability.

“We understand ASAT,” Cartwright said, using the military’s acronym for anti-satellite weaponry. “There’s no reason to go back and re-prove what we’ve already done.” And he said the satellite operation required modifications to the SM-3 missile that do not translate to an anti-missile mission.

“It doesn’t correlate,” said Cartwright, vice chairman of the Joint Chiefs of Staff. “Will I be able to convince everybody that that’s the case? No.”

One such sceptic may be China, which raised concerns about the satellite shoot-down before and after the fact.

On Thursday the Beijing government asked the US to release data on the shoot-down, and the Communist Party’s newspaper blasted what it called Washington’s callous attitude toward the weaponisation of space.

Asked about China’s concerns, Defence Secretary Robert Gates told reporters during a visit to US Pacific Command in Hawaii that the United States is prepared to share with China some of the information about the shoot-down, but he was not specific. He said some was provided beforehand.—AP