VANDENBERG AIR FORCE BASE, Calif. (AP) – The U.S. Air Force was preparing to test an unarmed Minuteman 3 intercontinental ballistic missile with a launch from California, the fourth such test this year. The 30th Space Wing says the missile was to be launched between 12:01 a.m. and 6:01 a.m. Wednesday from Vandenberg Air Force Base, about 130 miles northwest of Los Angeles. An Air Force statement said the test would show the effectiveness, readiness, and accuracy of the weapon system. Minuteman missiles are regularly tested with launches from Vandenberg that send unarmed re-entry vehicles 4,200 miles across the Pacific to a target area at Kwajalein Atoll. However, the latest U.S. launches come amid tensions with North Korea as that nation develops its own ICBMs.