North Korea threatened "all-out war" in response to exercises by South Korean and US troops due to start on Monday and told Seoul to stop cross-border propaganda, upping the rhetoric against its arch rivals.Pyongyang would respond to the upcoming drill, with "unprecedented all-out counteraction" that would turn the South's capital Seoul into a "sea of flames", the Korean Central News Agency said on Sunday.
"The army and people of the DPRK will return bolstered nuclear deterrent of our own style for the continued nuclear threat... and our own missile striking action for their vicious attempt to eliminate our missiles," KCNA said.
The statement was in contrast to more conciliatory comments it made earlier this year aimed at securing peace talks with the United States but came after Pyongyang officials stormed out of talks with the South this month.
Some 200,000 South Korean and 12,800 US troops will take part in the Key Resolve/Foal Eagle drills, which the North has labelled a preparation for war.
Key Resolve, a command post exercise involving computer simulation, will last until March 10. Part of Foal Eagle, a joint air, ground and naval training exercise, will continue through April 30.
The exercise reportedly includes scenarios such as localised provocations, tracing weapons of mass destruction, a sudden regime change in the communist state and an exodus of refugees, Yonhap news agency reported.
It also said the US planned to deploy it 97,000-tonne aircraft carrier USS Ronald Reagan for the drills.
Cross-border tension has been acute since the North's deadly shelling of a frontier island in November that killed four South Koreans including two civilians and sparked fears of war.
The first attack on civilians since the 1950-53 Korean War prompted Seoul to stage a series of military drills alone or with the United States and to expand regular exercises in a show of force against Pyongyang.
The South also revived a propaganda campaign across the heavily-fortified border targeting ordinary North Koreans -- a practice it had suspended since 2000 due to protests by the North.
Conservative opposition politician Song Young-Sun, citing a report from the defence ministry, said on Friday balloons carrying humanitarian supplies such as medicine and clothes were being launched across the border by the military.
She said the balloons also carried news of civil uprisings against repressive regimes in the Arab World and were aimed at getting information to the people of North Korea, who are largely cut off from the outside world.