S. Korea-US drill kicks off as North cuts hotline

The start of the two-week "Key Resolve" exercise follows a week of escalating tensions on the Korean peninsula, with North Korea lashing out over tightened UN sanctions adopted in response to its third nuclear test last month.

Pyongyang has condemned the joint manoeuvres as a provocative invasion rehearsal and announced that -- effective Monday -- it was scrapping the 1953 armistice ending the Korean War and voiding peace pacts signed with the South.

The South's Unification Ministry confirmed that the North appeared to have carried through on another promise to sever the hotline between Pyongyang and Seoul.

"The officials maintain contact by talking on the phone at 9:00am and 4:00pm every day. But the North did not answer our call this morning," a ministry spokeswoman said.

The hotline was installed in 1971 and the North has severed it on five occasions in the past -- most recently in 2010.

The Rodong Sinmun, the newspaper of the North's ruling communist party, confirmed in Monday's edition the "complete end" of the 1953 ceasefire which ended Korean War hostilities.

"With the ceasefire agreement blown apart ... no one can predict what will happen in this land from now on," the newspaper said.