Japan has sent its biggest warship on a mission to tighten ties with Southeast Asian countries it sees as potential allies in an effort to keep China’s regional sea territory claims in check.

Military officers from 10 Southeast Asian states have joined the Izumo helicopter carrier on a tour of waters that Tokyo invaded 75 years ago and where Beijing is now asserting its influence.

The four-day trip is high on symbolism and comes after a flurry of bilateral agreements for Japan to provide military aid to countries such as Vietnam and the Philippines that also have ocean boundary disputes with China. Increasingly tense territorial conflicts in both the South and East China Seas are entwined with Beijing’s broader goal to curb Washington’s long military supremacy in the Pacific.