Successful Missile Test

"This was the largest, most complex task that we've ever done," said Lieutenant General Patrick O'Reilly, director of the Pentagon's Missile Defense Agency.

But the target missile's countermeasures, intended to simulate decoys from enemy missiles -- precisely what critics of the defense shield doubt the system could overcome -- failed to deploy, he said.

"Countermeasures are very difficult to deploy," he said, adding that "there are many threats today that don't have countermeasures."

The interception took place at 3:29 pm (21:29 CET), Pentagon spokesman Bryan Whitman said, making the effort the eighth successful intercept out of the 13 tests conducted since 1999, with the last successful test taking place in September 2007.

Overall military chiefs approved of the effort.

"I am extremely pleased," said O'Reilly at a press briefing. "All the systems were working together," he added, referring to the complex alignment of radars, sensors and timing to coordinate the high-octane missile.

Brian Green, deputy assistant secretary of defense for strategic capabilities, added that the effort was an "operationally realistic test."

The effectiveness of the defense shield has been questioned by some scientists who claim the program would be unable to distinguish between a missile and a decoy -- precisely what failed to be realized in Friday's effort.

The test is seen as a crucial step towards a controversial anti-missile shield Washington plans to base in Eastern Europe.

The Bush administration wants to install a radar facility in the Czech Republic and 10 interceptor missiles in neighboring Poland by 2014.

The test of the project, which so far has cost the Defense Department some $100 billion, comes at a critical time before president-elect Barack Obama moves into the White House on January 20.

Obama has so far not committed to the missile defense shield.

One of his senior foreign policy advisors, Denis McDonough, has indicated however that Obama would support the program if the technology proves viable.

Opponent Russia still on edge

Moscow has repeatedly voiced strong objections to the shield plan, which Washington insists is not directed against Russia but at "rogue states" such as Iran and North Korea.

In late November Russian Prime Minister Vladimir Putin urged Obama to drop the planned shield in Eastern Europe.

"This project is aimed against the strategic potential of Russia. And we can only give it an adequate response," he said.

Earlier last month Moscow raised alarm in Western capitals by warning it could place missiles in the Russian exclave of Kaliningrad, close to Poland, in response to the plan.

On Friday the interceptor missile was launched from Vandenberg Air Force Base in California, as the target -- a fake warhead mimicking long-range ballistic missiles from nations like North Korea -- was set off from the Alaskan island of Kodiak.