WASHINGTON — The U.S. Missile Defense Agency (MDA) on June 6 successfully conducted the first flight test of a smaller version of its ground-based interceptor being developed as a backup option for a European missile shield, the agency said June 6.

The two-stage interceptor launched from Vandenberg Air Force Base, Calif., and delivered an operational kill vehicle to a target point in space, as opposed to actually intercepting a target missile, an MDA press release said. Program officials are still analyzing telemetry data from the test, but all indications are that it was a success, the release said.

The two-stage interceptor is derived from the three-stage Ground-based Midcourse Defense (GMD) interceptors now deployed in Alaska and California to defend the United States against long-range missiles. The MDA and GMD prime contractor Boeing Defense, Space & Security of St. Louis were developing the smaller variant to be deployed in Europe to defend allies and deployed forces there, but the White House has since changed course, relegating the interceptor to a backup option in favor of the Raytheon-built Standard Missile (SM)-3 interceptors.

Under a revised plan for European missile defense announced last year, U.S. Navy Aegis ships equipped with SM-3 interceptors will be deployed to European waters in 2011. Land-based SM-3 batteries will be developed and deployed in Poland and Romania in 2015. These interceptors have a successful test record against short- and medium-range ballistic missiles.

A larger and more capable version of the SM-3, known as block 2B, is needed to intercept long-range missiles and provide an additional layer of defense for the United States. It is being co-developed with Japan and is not expected to be ready until 2020. Development of the two-stage ground-based interceptor will continue as a hedge against technological problems with the larger SM-3 interceptor.