Chinese and Japanese vessels clashed rhetorically and at sea on December 2 in the latest flare-up around the Senkaku Islands (also known as Diaoyu Islands in China and Daioyuyai Islands in Taiwan), underscoring a deteriorating diplomatic climate between Asia’s two largest economies, local Japanese sources and the BBC have said.

China’s coast guard accused a Japanese fishing boat of entering what it described as Chinese territorial waters around the uninhabited island chain in the East China Sea. Its officers, according to state media, moved in to “warn off” the vessel and carried out what Beijing termed “necessary law-enforcement measures”. The islands are, however, Japan held and Tokyo has long rejected China’s territorial claim and a lesser claim by a Taiwanese county in the east of the self-governing island nation.

According to the BBC, Tokyo’s version diverged sharply. Japan’s coast guard said two Chinese vessels crossed into its territorial waters in the early hours of December 2, prompting a patrol ship to intervene and shield the fishing boat. The Japanese side said it ordered the Chinese vessels to leave and monitored the situation until they withdrew several hours later.

The latest run-in comes as relations sink to a new low following remarks by new Japanese prime minister, Sanae Takaichi, who told parliament last month that Japan could consider a military response if China launched an attack on Taiwan.

That comment provoked a swift backlash from Beijing, which regards the island as part of its territory. The friction has since spilled into broader political rhetoric and is increasingly shaping interactions between the two countries’ citizens.

The disputed island chain sits roughly 170km north-east of Taiwan and has been a persistent flashpoint. Although China and Japan agreed in principle in 2008 to pursue joint resource development in parts of the East China Sea, that accord has largely withered amid rising strategic rivalry. As a result, over the past decade, Chinese incursions into waters around the islands have grown more frequent, testing Japan’s capacity and resolve to enforce its administrative control.