U.S./S. Korea drills begin despite North Korean threat

South Korea and the U.S. kicked off annual military exercises Monday, a day after North Korea denounced the training as a rehearsal for invasion and threatened to attack the allies.

The exercises, dubbed Key Resolve and Foal Eagle, are aimed at rehearsing how to deploy U.S. reinforcements in time of an emergency on the Korean peninsula, U.S. military spokesman Kim Yong-kyu said. The U.S. stations about 28,500 troops in South Korea.

North Korea claims they amount to attack preparations and has demanded they be canceled. The North's military warned Sunday that it would bolster its nuclear capability and break off dialogue with the U.S. in response to the drills. It also said it would use unspecified "merciless physical force" to cope with them, saying it is no longer bound by the armistice that ended the 1950-53 Korean War.

Koh Yu-hwan, a professor at Seoul's Dongguk University, dismissed North Korea's statement as rhetoric. "The North's strong protest is not unusual as it also protested during previous drills," he said.