The US Missile Defense Agency (MDA) said a ground-based interceptor missile launched from Vandenberg Air Force Base in California hit a dummy armed missile in space that had been fired from Kodiak, Alaska.

The agency "successfully completed an important exercise and flight test involving the launch of an improved ground-based interceptor missile designed to protect the United States against a limited long-range ballistic missile attack," Air Force Lieutenant General Henry Obering, the agency's director, said in a statement.

The interception took place at 1746 GMT, agency spokesman Chris Taylor told AFP. The test initially had been scheduled Thursday but was postponed a day due to bad weather in Kodiak.

To downplay expectations, the US military warned in advance that the test was aimed primarily at determining whether the new ground-based interceptor could recognize its target, and not necessarily at interception itself.

It was the first test of the US missile defense system since North Korea's July 4 test-firing of six short- and medium-range missiles and a long-range missile, which all fell into the Sea of Japan (East Sea).

The US government estimates that North Korea's long-range missile could be capable of striking Hawaii, Alaska or even California, although officials acknowledge their intelligence on the matter is limited.

The US missile defense system employs radar and satellites to detect enemy missile launches and guide interceptors to their targets. The command center is based in Colorado and interceptor missiles are located in Alaska and at the Vandenberg air base.

The system is still under development, and before Friday only five of 10 test attempts to intercept an incoming ballistic missile had been successful.

Oberling said that Friday's test was the first successful intercept since October 2002.

Interceptor missiles had failed to launch from their silos in December 2004 and February 2005.

The capability of the US missile defense system to function under a real attack remains a subject of controversy, with even President George W. Bush recently saying it would have a "reasonable chance" to intercept an incoming North Korean missile.

Seven opposition Democratic legislators, including Representative Ike Skelton, sent a letter to Defense Secretary Donald Rumsfeld on Tuesday voicing concern about the reliability of the system and calling for a test "in operationally realistic conditions."

In the "highly scripted" tests, they wrote, "the time of the enemy launch was known; and the threat only came from a single enemy missile."

"We think we're on the right track," Obering said Friday at a news conference, adding that the MDA will make future tests "even more challenging."

The defense secretary said the positive results lent support to the effort.

"Successful tests such as these increase confidence in the approach to developing an initial missile defense capability," Rumsfeld said.

The next test is scheduled late this year or in early 2007 will have a principal goal of hitting the target.

Obering said the cost of each test typically ranges from 80 million dollars to 100 million dollars. Last weekend he said the agency planned an average of two or three tests per year.

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