Japan has dispatched its biggest warship, in the first such operation since it passed controversial laws expanding the role of its military. The helicopter carrier Izumo is escorting a US supply vessel within Japanese waters.
The US ship is heading to refuel the naval fleet in the region, including the Carl Vinson aircraft carrier group. North Korea has threatened to sink the Carl Vinson and a US submarine, amid rising tensions in the region.
Under Prime Minister Shinzo Abe, Japan is gradually pushing the limits of what its modern and powerful military is allowed to do, and with tensions high on the Korean peninsula, Mr Abe appears keen to try out the new laws for the first time, our correspondent says.