The helicopter carrier Izumo will leave the mother port of Yokosuka, south of Tokyo, on Monday and join the US supply ship to escort it further into the western Pacific, the leading Asahi Shimbun daily and Jiji Press reported citing unnamed government sources.
It will be the first deployment -- outside of troop exercises --to protect the US fleet after Prime Minister Shinzo Abe expanded the country's military capabilities in 2015, though they remain restricted under Japan's pacifist constitution.
The US supply ship is expected to support America's naval fleet in the Pacific, possibly including the aircraft carrier USS Carl Vinson, which remains on high alert over North Korea's ballistic missile firings, the reports said.
Japanese naval officials declined to comment on the reports.
