North Korea called on US military officers today to halt a joint training exercise with South Korean forces.
South Korean government officials have said Seoul is considering a delay of the Ulchi Focus Lens exercise, which are scheduled to run from August 20th-31st, so as not to derail a rare summit of the two Koreas at around the same time.
North Korea has said the drills could scupper a deal to end Pyongyang's nuclear weapons programme.
At a meeting of colonels from the North Korean military and US forces in South Korea, the North warned it "cannot remain a passive onlooker to it [the drills], doing nothing," Pyongyang's official KCNA news agency said.
The two Koreas are technically still at war because the 1950-1953 Korean War ended in a truce and not with a peace treaty. North Korea regularly protests against the annual exercises, which it has branded a prelude to invasion and nuclear war.
The North has also previously warned the drills have forced it to bolster its deterrent and it is prepared to counter-strike.