Rick Lehner, a spokesman for the Missile Defense Agency, declined to provide details about the counter-measures used.

Long-range missiles can mask their warheads with electronic jammers, chaff or decoys, which critics contend is an insurmountable weakness of the US missile defense shield.

"We launched a missile from Hawaii and it carried a package of what we call counter-measures. We used a variety of sensors to get data about those counter-measures as we flew," Lehner said.

"That helps us design a better interceptor so that we can defeat counter-measures as we make the intercepts," he said.

The Pentagon has not had a successful long-range missile intercept test since October 2002.

Of three tests since then, one failed in December 2002 because the interceptor's "kill vehicle" did not separate from the booster. In the next two tests in 2004 and 2005 the interceptor failed to launch.

The next intercept test is expected to take place this summer, Lehner said. The primary objective will be to test an upgraded radar in northern California at Beale Air Force Base, he said.

He would not say whether the interceptor missile will be going against a target that employs counter-measures in that test.

Related Links
-