North Korea accused the United States Monday of building up military forces in the region and vowed to strengthen its own defences "in every way".
The comments came one day after the communist state said it would bolster its nuclear deterrent in the face of what it called US antagonism.
Tensions on the peninsula have been high in recent months, following repeated threats by Pyongyang against Seoul and the North's failed long-range rocket launch in April.
A spokesman for the North's foreign ministry said Monday the US "arms buildup" is an "open provocation" to Pyongyang and a prelude to a regional war.
The spokesman's comments on the official news agency cited the disclosure last week that US forces based in the South are seeking more attack helicopters and stronger missile defence systems.
The spokesman also mentioned a naval exercise involving South Korea, the US and Japan, which will be held Thursday and Friday south of the peninsula.
South Korean and US naval forces, including a US aircraft carrier, will also hold manoeuvres in the Yellow Sea for three days starting Saturday.
The North also blasted last Thursday's meeting in Washington between the US and South Korean defence and foreign ministers.
It said their aim was to discuss "making South Korea an advance base for the implementation of the US strategy for domination over Asia".
Seoul said the ministers had agreed there would be "a very decisive response" to any fresh provocation from Pyongyang.
The South accuses the North of torpedoing a warship in March 2010 with the loss of 46 lives. The North denied the charge but killed four South Koreans when it shelled a border island in November 2010.
Some Seoul analysts believe it may engineer another border clash as new leader Kim Jong-Un tries to bolster his status with the military.
There is also speculation the North will conduct another nuclear test following United Nations censure of its rocket launch, although Pyongyang has said it has no plans at present to do so.
The North said the US arms buildup "is a prelude to a regional war targeting not only the DPRK (North Korea) but also several Northeast Asian countries..."
The North would "increase its self-defence capabilities in every way to protect sovereignty and dignity of the country and nation".