The United States defence department says the missile defence system on Kwajalein Atoll in the Marshall Islands has failed to intercept an incoming test missile.
The Missile Defense Agency says it's the second failure of the experimental programme in as many months.
A statement said the cause of the failure yesterday was under investigation.
A spokesman for the agency, Rick Lehner, said the early indications was that there had been a malfunction with the ground support equipment at the test range on Kwajalein Island.
Previous failures of these US$85 million test launches have been regarded as significant setbacks by critics of the programme.