The U.S., South Korea and Japan held a joint maritime drill this week on countering submarine-launched ballistic missiles and other “underwater threats” from North Korea, the ROK navy announced on Friday, with a U.S. aircraft carrier taking part.

The drill on Thursday and Friday in international waters off the southern coast of Jeju Island followed the countries’ first trilateral joint aerial exercises of the year last week, as well as a summit between Japanese Prime Minister Fumio Kishida and U.S. President Joe Biden on Wednesday.