A U.S. aircraft carrier has visited South Korean waters for the first time in nearly six months to participate in joint drills, as North Korea continues to fire ballistic missiles it has described as warnings to the allies.

The nuclear-powered aircraft carrier USS Nimitz is part of a carrier strike group that sailed near Jeju Island on Monday to conduct maritime drills with the ROK navy and will move to Busan Naval Base the following day, according to the South Korean defense ministry.