Japanese sub calls at ex-US naval base

Mission to Philippines comes day before Manila and Washington begin joint military exercise

A Japanese submarine visited a former US navy base at Subic Bay in the Philippines on Sunday - the first such visit in 15 years - in a sign of deeper international involvement in territorial disputes in the South China Sea.

The base is just 200 kilometers from China's Huangyan Island, the scene of confrontations between Chinese and Filipino ships in 2012.