An unarmed Minuteman 3 nuclear missile roared out of its underground bunker on the California coastline on Thursday and soared over the Pacific, inscribing the signature of American power amid growing worry about North Korea’s pursuit of nuclear weapons capable of reaching US soil.

When it comes to deterring an attack by North Korea or other potential adversaries, the missile is the message.

At 11:01pm Pacific Standard Time on Thursday, the Minuteman missile, toting a payload of test instruments rather than a nuclear warhead, leaped into the darkness in an explosion of flame. It arced toward its test range in the waters of the Kwajalein Atoll, an island chain about 2500 miles (4000km) southwest of Honolulu.

About 30 minutes later the re-entry vehicle that carries the missile’s payload reached its target, Colonel Craig Ramsey, commander of the 576th Flight Test Squadron, told an assembled group of observers, including Deputy defence Secretary Robert Work and Admiral Cecil Haney, the top nuclear war-fighting commander.

Aside from confirming technical soundness, Minuteman test launches are the US military’s way of sharpening the message that forms the foundation of US nuclear deterrence theory – that if potential attackers believe US nuclear missiles and bombs are ready for war at all times, then no adversary would dare start a nuclear fight.

The credibility of this message can be damaged by signs of weakness or instability in the nuclear weapons force. In 2013-14 the Associated Press documented morale, training, leadership and equipment problems in the Minuteman force, and in January the Air Force acknowledged to the AP that errors by a maintenance crew damaged an armed Minuteman in May 2014.

Work said ahead of Thursday’s launch that he sees good progress in fixing the problems in the nuclear missile corps. He also said the Vandenberg test launches are critically important.

“It is a signal to anyone who has nuclear weapons that we are prepared to use nuclear weapons in defence of our country, if necessary,” he said, adding later, “We do it to demonstrate that these missiles – even though they’re old – they still remain the most effective, or one of the most effective, missiles in the world.”