North Korea on Wednesday called into question a much-anticipated and unprecedented summit between its leader Kim Jong-un and US President Donald Trump, the South's Yonhap news agency reported.
Pyongyang also cancelled high-level talks due Wednesday with Seoul over the Max Thunder joint military exercises between the US and the South, Seoul said.
The US will "have to undertake careful deliberations about the fate of the planned North Korea-US summit in light of this provocative military ruckus", Yonhap quoted the North's official news agency KCNA as saying.
The drills between the two allies' air forces were a rehearsal for invasion and a provocation at a time when inter-Korean relations were warming, it cited KCNA as adding.
The language used is a sudden and dramatic return to the rhetoric of the past from Pyongyang, which has long argued that it needs nuclear weapons to defend itself against the US.
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Hostilities in the 1950-53 Korean War stopped with a ceasefire, leaving the two halves of the peninsula divided by the Demilitarised Zone (DMZ) and still technically at war.
At a dramatic summit last month in Panmunjom, the truce village in the DMZ, Mr Kim and the South's President Moon Jae-in pledged to pursue a peace treaty to formally end the conflict, and reaffirmed their commitment to denuclearising the Korean peninsula.
But the phrase is open to interpretation on both sides and the North has spent decades developing its atomic arsenal, culminating last year in its sixth nuclear test - by far its biggest to date - and the launch of missiles capable of reaching the US.
The drive has seen it subjected to multiple rounds of UN Security Council resolutions, while Trump threatened it with "fire and fury" as he and Kim traded personal insults and threats of war last year.
