The Pentagon was forced to abort a bid to shoot down a long-range missile over the Pacific Friday when it failed to fly high enough to engage the missile defense system, US officials said.
"The target did not reach sufficient altitude to be deemed a threat and so the Ballistic Missile Defense System did not engage it, as designed," said Air Force Lieutenant General Henry Obering.
The scheduled flight test was therefore not completed and deemed a "no" test, he said, adding an investigation would now try to "determine the cause of the malfunction."
The failure to complete the test comes as a blow to the program at a time when the United States is negotiating to install missile interceptors and a radar in Poland and the Czech Republic over vehement opposition from Moscow.
The agency had hoped to test the missile defense system by shooting down a long-range test missile launched from the Kodiak complex in Alaska with interceptors fired from the Vandenberg Air Force base in California.
But Obering said there was "always a risk of this occurrence since we are flying old intercontinental ballistic missile motors in our targets.
"We have initiated a target modernization program within our existing budget, which should mitigate these risks for the future," he said, adding the agency would try to repeat the test later this summer.
It was the second time that US officials tested the system with all its operational components -- a complex network of radars, command centers and an interceptor missile topped with a "kill vehicle."
If it had been successful the kill vehicle would have collided at high speed with the mock warhead in space over the Pacific, pulverizing it.
