The United States successfully tested a long-range, nuclear-capable ballistic missile Tuesday after twice postponing the launch to avoid stoking tensions over Ukraine and Taiwan, the Air Force announced.

The Air Force Global Strike Command launched the unarmed Minuteman III intercontinental ballistic missile over the Pacific from Vandenberg Space Force Base in California just after midnight local time.

The missile carried a test re-entry vehicle, which in a strategic conflict could be armed with a nuclear warhead.

The re-entry vehicle travelled about 4,200 miles (6,760 kilometres) to the Kwajalein Atoll in the Marshall Islands in the western Pacific.

"This test launch is part of routine and periodic activities intended to demonstrate that the United States’ nuclear deterrent is safe, secure, reliable and effective," the Air Force said in a statement.

"Such tests have occurred more than 300 times before, and this test is not the result of current world events."

The test was originally scheduled in March but was put off to avoid adding to tensions over Russia's February 24 invasion of Ukraine.

It was postponed a second time at the beginning of August as military tensions soared over China's test launches of multiple ballistic missiles and live-fire exercises in reaction to the visit of the top US lawmaker, Nancy Pelosi, to Taiwan.

"As China engages in destabilizing military exercises around Taiwan, the United States is demonstrating instead the behaviour of a responsible nuclear power by reducing the risks of miscalculation and misperception," White House national security spokesman John Kirby said at the time, explaining the postponement.