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

TOKYO (AP) — Japan and Australia urged calm on Sunday after Chinese military aircraft locked radar on Japanese fighter jets, a month after the Japanese leader’s recent remarks on Taiwan that stirred tensions between Tokyo and Beijing.

In a now deleted social media post, the Consul General of the People’s Republic of China to the Japanese city of Osaka recently threatened to “cut off” Japanese Prime Minister Sanae Takaichi’s “filthy head.

China and Japan ties, already frayed by comments made by Prime Minister Sanae Takaichi on Taiwan, came under further strain at the weekend after a Chinese fighter aircraft trained fire-control radar on Japanese military jets for the first time.

Japan's Defense Minister Koizumi Shinjiro has again expressed concern over Chinese military aircraft directing radar at Japanese Air Self-Defense Force fighter jets over international waters off Okinawa's main island in southern Japan on Saturday.

The Japanese government is taking uncomfortable steps to prepare its citizens for a possible future war that its military would not be able to avoid.

The buildup comes as Beijing steps up pressure on Prime Minister Sanae Takaichi over her recent remarks suggesting Japan might intervene militarily if China were to attempt to seize Taiwan

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

TAIPEI/TOKYO, Dec 5 (Reuters) - Taiwan and Japan voiced concern on Friday over Chinese military activities in the region, after Reuters reported that Beijing had deployed a large number of vessels across East Asian waters this week in its largest maritime show of force to date.