The commander of US troops in South Korea warned Pyongyang his forces are prepared for war, escalating tensions on the peninsula as North Korea claimed its new long-range missile can carry a “large nuclear warhead”.

The stark statement from General Vincent Brooks came as part of a joint US-South Korean missile exercise off the country’s east coast, conducted just hours after both Washington and Seoul confirmed North Korea’s claims that it had successfully tested its first intercontinental ballistic missile.

“Self-restraint, which is a choice, is all that separates armistice and war,” said Gen Brooks after the joint exercise yesterday, in which a barrage of “precision strike” missiles was fired. “As this alliance missile live fire shows, we are able to change our choice when so ordered by our alliance national leaders.”