The US this week achieved a goal that has eluded it since Ronald Reagan's Star Wars programme by knocking out a ballistic missile using a high-powered laser beam mounted on a plane.

The successful test was carried out yesterday in California, the US Missile Defence Agency (MDA) said, making real what had previously been confined to the realms of science fiction.

The plane uses a combination of lasers to lock on to the missile and track its trajectory, and then bring it down with a single shot fired from the nose turret, all in less than 12 seconds.

According to analysts, the breakthrough could have an impact on the North Korean and Iranian missile programmes, forcing them to develop faster missiles and adopt measures to counter the laser beams. The MDA said today: "The revolutionary use of
directed energy is very attractive for missile defence, with the potential to attack multiple targets at the speed of light, at a range of hundreds of kilometres, and at a low cost per intercept attempt compared to current technologies."

Work on the laser weapons system has been under way in earnest for at least a decade, at a cost of more than $1bn. In the past, laser beams have been used successfully against stationary targets from stationary platforms, but in this test the beam was directed from a plane against a moving target, a much more challenging feat.

However, some scientists and military analysts expressed scepticism about its long-term viability, saying that other such projects that had been hailed as revolutionary did not work when confronted by all the problems thrown up by war.

Michael Elleman, a senior fellow for missile research in the Washington office of the
International Institute for Strategic Studies, traced a direct line from the controversial programme set out by Reagan three decades ago that was dubbed Star Wars, which envisaged lasers based in outer space intercepting missiles. "Reagan had a grand vision but did not know what the architecture would look like. They were looking more at space-based laser technology. The laser [in the latest test] is not necessarily what Reagan envisaged but it fits inside the grander scheme of what he wanted to achieve."

Elleman said the laser could force North Korea, whose Unha missile is slow, to look at accelerated missiles and that Iran was already doing this.

The MDA said the test was carried out at Point Mugu's Naval Air Warfare Centre near Ventura.

"The Missile Defence Agency demonstrated the potential use of directed energy to defend against ballistic missiles when the Airborne Laser Test-bed (ALTB) successfully destroyed a boosting ballistic missile," the agency said.

The system is being developed by ­Boeing, which uses the airframe of a modified 747 jumbo, and the MDA. Aerospace and defense contractor Northrop Grumman supplies the higher-energy laser, while Lockheed Martin is developing the beam and fire control systems.

"This was the first directed energy lethal intercept demonstration against a liquid-fuel boosting ballistic missile target from an airborne platform," the agency added.

The system successfully intercepted a missile in August last year but did not bring it down.

Last year the defence secretary, Robert Gates, decided that the programme should be scaled back, keeping research to a single plane, because of scepticism about how practical it would be.

John Pike, a defence analyst and founder of Virginia-based Global Security, said he doubted the test would change Gates's view. "Gates seemed to believe that there was no prospect of the plane engaging targets at ranges of several hundred kilometres, and that engagements at ranges of less than 100 kilometres were not militarily interesting," he said.

The MDA statement did not specify what the range was during the test.

Ivan Oelrich, a physicist and vice-president for strategic security programmes at the Federation of American Scientists, said: "What would be interesting would be how far away it [the missile] is." He said that to be useful, the laser would have to be able to shoot down missiles from at least 100 miles. It would also be expensive to keep one or more planes on stations waiting for a missile.