SEOUL (AP): The US Air Force has tested a missile on the same day that North Korea is suspected of having launched two short-range missiles.

The Air Force says it launched a Minuteman 3 intercontinental ballistic missile on Thursday from Vandenberg Air Force Base in California.

It says the launch was part of regularly scheduled tests of ICBMs to ensure they are ready for potential combat. It said the test was unrelated to any world events. It was the second such test in a little over a week. The Air Force normally does four or five such tests each year.

The ICBM test launches are planned months in advance.

The Air Force moved a Minuteman 3 missile from a launch silo controlled by the 90th Missile Wing at F.E. Warren Air Force Base in Wyoming to the launch site at Vandenberg.

North Korea's launch was its second in five days and a possible warning that nuclear disarmament talks with Washington could be in danger.

South Korea's military says North Korea has fired two suspected short-range missiles.

South Korea's Joint Chiefs of Staff earlier said North Korea fired at least one projectile from its western province on Thursday afternoon.

The Joint Chiefs of Staff said later that the North fired what appeared to be two short-range missiles.

It says they flew 420 kilometers (260 miles) and 270 kilometers (167 miles), respectively.

It says South Korean and U.S. authorities are trying to find out more details about the launches.