North Korea dramatically escalated its warlike rhetoric on Thursday, warning that it had authorised plans for nuclear strikes on targets in the United States.

“The moment of explosion is approaching fast,” the North Korean military said, warning that war could break out “today or tomorrow”.

Pyongyang’s latest pronouncement came as Washington scrambled to reinforce its Pacific missile defences, preparing to send ground-based interceptors to Guam and dispatching two Aegis class destroyers to the region.

Tension was also high on the North’s heavily fortified border with South Korea, after Kim Jong-Un’s isolated regime barred South Koreans from entering a Seoul-funded joint industrial park on its side of the frontier.

In a statement published by the state KCNA news agency, the Korean People’s Army general staff warned Washington that US threats would be “smashed by… cutting-edge smaller, lighter and diversified nuclear strike means”.