WASHINGTON (AFP) - The US Air Force delayed for a day an intercontinental ballistic missile test on Tuesday because of a "range safety instrumentation issue".
The air force will try again to launch the unarmed Minuteman 3 missile on Wednesday - between 3.01am and 9.01am local time (6.01pm Wednesday and 12.01am Thursday Singapore time) - from California's Vandenberg Air Force Base, the air force said.
The missile's trajectory will be towards the Kwajalein Atoll in the Marshall Islands - about 7,000 kilometres across the Pacific.
The air force did not explain the latest delay except to say it was due to a "range instrumentation safety issue."
"Extensive resources are devoted to every launch mission to ensure safety in our local area and downrange," Colonel Brent McArthur, who decides when to launch, said in a statement.
"Public safety is my first priority during all launch operations."
The test was delayed last month to avoid stoking tensions with North Korea, which had deployed two medium-range Musudan missiles to its east coast, threatening strikes, including with nuclear warhead.
Tensions have abated, with US intelligence reporting that the weapons were removed from their launch pads in early May.
But North Korea in recent days has fired off a six short-range missiles in tests.
"These tests provide us the opportunity to demonstrate the readiness of the ICBM force," said Colonel Richard Pagliuco, commander of the 576th Flight Test Squadron, in a statement.
"Every test provides valuable data regarding the accuracy and reliability of the weapon system."
Some of the soldiers participating in US test come from the Minot Air Force Base in North Dakota, where 17 officers recently lost their certification to control ICBMs after a poor performance review.
The US has some 450 Minuteman 3 missiles, stored in silos on three bases including Minot, Warren Air Force Base in Wyoming, and Malmstrom Air Force Base in Montana.
The missile has been in service since the early 1970s and the Air Force plans to continue upgrading them through 2030.
