NKorea puts troops on alert over military drill

The communist state's military supreme command, in a report on official media, described the exercise south of the border as a "grave threat" to peace and a prelude to an invasion, AFP reported.

It vowed to respond to "even the slightest military provocation" infringing on its sovereignty with a "merciless and prompt annihilating strike at the aggressors with all offensive and defensive means including nuclear deterrent involved."

The nuclear-armed North frequently denounces such exercises, which Seoul and Washington say are purely defensive, and vows to retaliate for any breach of its sovereignty.

As it routinely does, the US and South Korean military command has notified the North of the "Ulchi Freedom Guardian" exercise from August 17-27.

Some 10,000 US troops from bases in South Korea and overseas, plus about 56,000 South Korean troops, will take part.

The US-South Korean command has said the operations are defensive and "not meant to be provocative in any way."

The North's military said the exercise, one of two large-scale annual manoeuvres staged in the South, is based on a new scenario for invasion.

"The army and people of the DPRK (North Korea) will never remain a passive onlooker to the prevailing touch-and-go situation where dark clouds of a nuclear war are gathering to hang heavily over the inviolable territory of their country," according to the report on the Korean Central News Agency.

International tensions have grown this year after the North staged another long-range missile test and nuclear test and the United Nations imposed tougher sanctions.

The North said its regular military and other forces would closely track the exercise and launch an immediate strong attack in response to any intrusion.

It told its people to adopt a "tense and militarised posture" as they pursue a "150-day campaign" -- a drive now under way to raise productivity in key sectors of the economy.

The US stations 28,500 troops in the South.