In a statement issued via state media on Monday, the North Korean Foreign Ministry called the Freedom Shield drills "a dangerous provocative act of leading the acute situation on the Korean peninsula, which may spark off a physical conflict between the two sides by means of an accidental single shot, to the extreme point."

North Korea launched several ballistic missiles toward the Yellow Sea on Monday afternoon, Seoul's military said, on the first day of a large-scale joint U.S-South Korea military exercise on the Peninsula.

"South Korean military has increased surveillance and maintaining readiness posture in close cooperation with the U.S.," South Korea's Joint Chiefs said on Monday.