North Korea fired "multiple unidentified ballistic missiles" on Monday, South Korea's military said, the same day Seoul and Washington began a major annual joint military drill known as Freedom Shield.

The U.S. aircraft carrier USS Carl Vinson arrived at the southern port city of Busan in South Korea on Sunday as a show of force against North Korea, South Korea's navy said.

A U.S. aircraft carrier has arrived in South Korea in a show of force, days after North Korea test-launched cruise missiles to demonstrate its counterattack capabilities.

The North Korea Foreign Ministry said U.S.-South Korea joint military exercises are "a dangerous provocative act," state media KCNA reported on Monday. Annual South Korean and U.S. military exercises called Freedom Shield are due to begin on Monday and run until March 20.

North Korea fired several ballistic missiles into the sea after South Korean and U.S. troops began their large annual combined drills, Seoul said.

North Korea launched several ballistic missiles off its western coast Monday, the same day the United States and the South kicked off Freedom Shield, an annual, large-scale military exercise. The missiles were fired at around 1:50 p.