The United States, Australia, Japan and the Philippines are planning anti-submarine drills in the South China Sea on April 7, Kyodo news agency reported on Tuesday.

It would mark the first such full-fledged exercise for the navies of the four countries in those waters and is likely aimed at demonstrating solidarity with the Philippines against China's growing assertiveness, Kyodo said, citing multiple people familiar with the matter. (Reporting by Kantaro Komiya Editing by Chang-Ran Kim)