VANDENBERG AIR FORCE BASE, Calif. -- The U.S. Air Force has test-launched an unarmed Minuteman 3 intercontinental ballistic missile from California.

The missile lifted off from Vandenberg Air Force Base at 3:33 a.m. PDT (1033 GMT) Thursday.

It was the second Minuteman launch from Vandenberg this week. The first was launched early Sunday.

The Air Force Global Strike Command said the test was a success. No other details were released because it was a classified mission. Such tests typically involve a flight over the Pacific Ocean to a target in the Kwajalein Atoll.

Col. Scott Fox, vice commander of the 20th Air Force, said in a statement that the test was a visible demonstration of the nation's nuclear deterrent.

Private rocket maker SpaceX will attempt to launch a Canadian satellite from Vandenberg on Sunday.