The military said it shot down an intermediate-range ballistic missile target over the Pacific on Friday in the most challenging test yet of its work on a planned antimissile shield for Europe against Iran.

The Pentagon said the successful test of Lockheed Martin Corp and Raytheon Co hardware demonstrated the capability of the first phase of a layered, multibillion dollar antimissile shield, which is due to be in place in Europe by year-end.

The technology may also be adapted to defend against North Korea, another focus of U.S. antimissile efforts, and ultimately to bolster existing ground-based defenses.

The test west of Hawaii marked the first time Lockheed's shipboard Aegis combat system had been used to intercept a target with a range greater than 1,900 miles, said the Pentagon's Missile Defense Agency, or MDA.

Dubbed Flight Test Standard Missile-15, it was also the first Aegis test to rely on missile tracking data gathered by a powerful on-shore radar station.

The ability to use remote radar data to counter an enemy ballistic missile greatly increases the battle space and defended area of the Standard Missile-3 interceptor built by Raytheon and used to destroy the target, MDA said.

Previous sea-based Aegis intercept tests have featured shorter-range targets.

This was the 21st successful intercept in 25 attempts for the Aegis program since flight testing began in 2002, the agency said.

The last two intercept tests of a U.S. ground-based antimissile bulwark, managed by Boeing Co and aimed at protecting U.S. soil from even longer-range missiles, have failed.

FLEXIBLE TECHNOLOGY

President Barack Obama in September 2009 scrapped a George W. Bush-era plan to build in Poland and the Czech Republic a European version of the ground-based shield already deployed in California and Alaska.

Instead, Obama's Pentagon turned to the more flexible Aegis technology to adapt more readily to evolving threats and the geography of each region, Navy Rear Admiral Archer Macy, head of the joint military staff's antimissile office, said in congressional testimony on Wednesday.

In the test Friday, an intermediate-range ballistic missile target was launched in a northeasterly direction from Kwajalein Atoll in the Republic of the Marshall Islands, about 2,300 miles southwest of Hawaii.

A Raytheon-built, forward-based AN/TPY-2 X-band transportable radar, located on Wake Island, detected and tracked the target, MDA said.

The radar sent information to a battle management system that relayed cues to the destroyer O'Kane west of Hawaii. The ship aimed and launched Raytheon's SM-3 Block IA missile 11 minutes after the target was launched, MDA said.

Initial indications are that all components performed as designed, it said.

Richard Lehner, an MDA spokesman, declined to say whether the test included any countermeasures, such as decoys that an enemy likely would use. He cited security requirements.

But unless such countermeasures are included, MDA's tests simply cannot tell us whether the system would work in the real world, said Tom Collina, research director at the private Arms Control Association.

The United States expects to meet its goal of putting an initial missile defense capability in Europe by the end of this year even though efforts to find a host nation for the Raytheon-built X-band radar station are still under way, Brad Roberts, a deputy assistant secretary of defense, told the House of Representatives Armed Services subcommittee on strategic forces on March 31.

Both North Korea and Iran have developed and deployed medium-range ballistic missiles, with a range of 625 to 1875 miles.

Neither has successfully flight-tested either intermediate range or intercontinental-range ballistic missiles, said Greg Theilmann, an Arms Control Association missile expert who formerly assessed foreign ballistic missile threats in the U.S. State Department's intelligence bureau.

(Editing by Jackie Frank and Todd Eastham)