Japan has dispatched its biggest warship, Izumo, to escort US supply vessels including the Carl Vinson aircraft carrier group. The helicopter carrier Izumo is the first warship deployed outside of exercises under new laws passed in 2015 that allow Japan to come to the aid of an ally under attack known as collective self-defence.

The Izumo’s deployment follows recent joint exercises conducted by Japan and the US, and other naval developments amid increased tensions. Japan’s post-World War Two constitution bars its military from using force to resolve conflicts except in cases of self-defence.

The legislation allows the Self-Defense Forces(SDF) to guard US ships engaged in such activities as joint exercises and the monitoring of possible ballistic missile launches.