Two Japanese destroyers have left a port in western Japan, as a US aircraft carrier and other ships are heading for waters off the Korean Peninsula. Japan's Defense Ministry says a joint drill with the US fleet is being considered.
On Wednesday, a White House spokesman told reporters that the USS Carl Vinson strike group was heading to the Korean Peninsula.
The 2 Maritime Self-Defense Force destroyers set sail from Sasebo in Nagasaki Prefecture on Friday morning.
Defense Ministry officials say the details of the joint exercise have yet to be determined.
US Defense Department officials say the aircraft carrier is expected to enter the Sea of Japan early next week.
A joint drill would display Japan-US cooperation against North Korea, which will mark the 85th anniversary of the foundation of the Korean People's Army on April 25th.