North Korea has condemned plans for a joint military exercise between South Korea and the US later this month.
The joint exercises are held annually
Pyongyang called the 11-day exercise an "intolerable act of provocation" that threatened recent progress over its nuclear programme.
The North regularly denounces the annual Ulchi Focus Lens drill as preparation for an attack against it.
Seoul and Washington insist the exercises, which began in 1975, are purely for defensive purposes.
The Ulchi Focus Lens drill, which is this year set for 20-31 August, is one of the world's largest computer-simulated war games.
This year, it is expected to involve 10,000 US troops, most of them stationed in South Korea, and an undisclosed number of South Korean troops.
North Korea's Committee for Peaceful Reunification of the Fatherland denounced the war games in a statement carried on the country's official media.
The drill is "an intolerable act of provocation, which is driving the situation on the Korean peninsula to a phase of extreme confrontation", the statement said.
The committee said the exercise "poses obstacles to efforts to resolve" the nuclear disarmament issue and improving inter-Korean relations.
The North warned that it would respond by working to "further solidify our war deterrent".
The North frequently uses the word "deterrent" when referring to its nuclear programme, correspondents say.
Pyongyang provoked international alarm and condemnation last October after carrying out its first nuclear test.
But last month, the North shut down its only functioning nuclear reactor, Yongbyon, as part of a landmark deal agreed at multi-party talks in February.
Efforts are now under way for the North and its partners in the talks - the US, China, South Korea, Japan and Russia - to move on to the next phase of the deal, which involves permanently disabling its nuclear facilities.