The U.S. has conducted a test of its Terminal High Altitude Area Defense (THAAD) defense system in Alaska by launching a ballistic missile over the Pacific Ocean, military officials said early Sunday.

The weapon was fired by a U.S. Air Force plane and intercepted by the system, the Missile Defense Agency (MDA) said, describing the test as “successful.”

The exercise will help the U.S. “to stay ahead of the evolving threat,” said MDA Director Lt. Gen. Sam Greaves in a statement, without elaborating.

Earlier this month, U.S. officials told Reuters that the military was planning a test amid tensions with North Korea. The U.S. has THAAD interceptors in Guam that are meant to help guard against a missile attack from a country such as North Korea.