An unarmed intercontinental ballistic missile has been launched from California to test the defense system, the US Air Force Global Strike Command said. The Minuteman III missile lifted off from Vandenberg Space Force Base at 11:01 p.m. Thursday and its reentry vehicle traveled about 4,200 miles (6,800 kilometers) over the Pacific Ocean to the Kwajalein Atoll in the Marshall Islands, an Air Force statement said. While the test occurred amid US concerns about North Korea's missile tests and the transit of a Chinese spy balloon across the United States, the Air Force said the launch was routine. “Such tests have occurred over 300 times before, and this test is not the result of current world events,” the statement said. The Minuteman III system has been in service for decades. The Air Force plans to replace it with a new missile called the Sentinel. “Until full capability is achieved in the mid-2030s, the Air Force is committed to ensuring Minuteman III remains a viable deterrent,” the service said.