North Korea raises military alert ahead of South drill: Report

North Korea's military has raised an alert for its artillery units on the west coast in readiness for a planned live-fire drill by the South, Yonhap news agency quoted a government source as saying on Sunday. 

"We understand that there's been an upgrade in alert at artillery units," the government source was quoted as saying.                   

South Korean marines are expected to stage live-fire drills off its Yeonpyeong island off the peninsula's west coast some time before nightfall on Tuesday.