The United States on Wednesday tested an unarmed Minuteman III intercontinental ballistic missile with a new kind of re-entry vehicle as it seeks to modernize aging surface-to-air weapons.

The missile was launched at 0830 GMT from Vandenberg Air Force Base in California, soaring 4,200 miles (6,700 km) across the Pacific to the Kwajalein atoll in the Marshall Islands, the air force said in a statement.

It said it was a "developmental test launch," not a routine test launch like one carried out on October 2. "Rather than randomly selecting a fielded ICBM to verify fleet-wide reliability, a Developmental Test Launch uses a spare missile from storage to validate flight worthiness of new or replacement components in an as-near-to operational environment as possible," the statement said.