The Pentagon said that the Ballistic Missile Defence Organisation and the US army had conducted a "successful intercept with a target by the Theater High Altitude Area Defence (THAAD) missile" at the White Sands missile range in New Mexico.
In other words, it had successfully used a missile to destroy another missile, a technological capability crucial to a missile defence system.
The successful test was the 10th of a 13-test series and followed six attempts in which the missile missed its target. This record prompted President Bill Clinton to order the military to review the multi-billion- dollar programme only last month.
In the latest test, conducted at dawn yesterday, a Hera test rocket was intercepted in flight by another missile over the White Sands range. If the technology becomes reliable, the US will be able to destroy scud ballistic missiles such as those fired by Iraq during the Gulf War before they reach their intended targets.
Earlier this year, President Clinton bowed to pressure from the Republican- controlled Congress to proceed with the missile defence programme, and committed more than $6bn (pounds 3.75bn) to a national missile defence programme. But thetest failures raised questions about the reliability of the system being developed by Lockheed Martin for the US Army.
The last failed test, on 29 March, made the company liable to forfeit $15m under the terms of its Pentagon contract.