The USS Aircraft Carrier Carl Vinson made a port call in South Korea’s southern Harbour city of Busan today to participate in the annual U.S.-South Korea military exercises.

The nuclear-powered aircraft carrier arrived in Busan to lead a strike group made of up to twelve surface ships, and nine aircraft squadrons.

South Korean and U.S. Troops began the large-scale joint drills, which are billed as defensive in nature, on March 1.

North Korea warned the united states of “merciless” attacks if the carrier infringes on its sovereignty or dignity during U.S.-South Korean drills.

Last week, North Korea fired four ballistic missiles into the sea off Japan in response to annual U.S.-South Korea military drills, which the north sees as preparation for war.