Japan and the United States held a joint exercise involving their Aegis-equipped ships in the Sea of Japan on Tuesday, amid heightened tension over North Korea.

The Maritime Self-Defense Force had already conducted an exercise involving its destroyers and the U.S. nuclear-powered carrier Carl Vinson on Sunday and Monday in the Philippine Sea.

As the U.S. carrier is believed to be approaching waters near the Korean Peninsula, the MSDF is considering holding another joint drill in the Sea of Japan, according to a Japanese government source. It is rare for the MSDF to hold an exercise with a U.S. carrier in the waters.