As relations with China continue to deteriorate, Japan is embarking on its biggest military buildup in at least four decades.

Japan is threatening China militarily which is "completely unacceptable", Chinese Foreign Minister Wang Yi told his German counterpart, after Japan said that Chinese fighter jets had aimed their radar at Japanese military aircraft.

No end in sight to spat between Japan and China over Taiwan, as neither Tokyo nor Beijing shows signs of backing down.

China and Japan are two of Asia’s most powerful nations and the region’s biggest trading partners. Yet centuries of intense rivalry mean their economic embrace can never be taken for granted.

China is deploying a large number of naval and coast guard vessels across East Asian waters, at one point more than 100, in the largest maritime show of force to date, according to four sources and intelligence reports reviewed by Reuters.