Washington has said it looks forward to resuming disarmament talks with North Korea despite a threat by Pyongyang on Tuesday that it might call off its suspension of its 20-month nuclear and missile tests.

The latest missive by the North Korean foreign ministry pre-empted a planned joint US-South Korea military exercise in August, which it called “a rehearsal of war, aimed at militarily occupying our Republic by surprise attack.”

The statement said that Donald Trump, the US president, had pledged to suspend the military drills at his first historic summit with Kim Jong-un in Singapore last year, which he reiterated at another unprecedented meeting of the two leaders last month on the border between the North and South.

It pointed out that its own earlier declaration of a moratorium on nuclear and intercontinental ballistic missile tests was made to improve ties and “not a legal document inscribed on paper.”

It added: “With the US unilaterally reneging on its commitments, we are gradually losing our justifications to follow through on the commitments we made,” stressing the military drill would also affect talks if it went ahead.