Ships from Japan's and China's coast guards faced off near disputed islands Tuesday, with each claiming they drove out the other's vessels that had intruded into their territorial waters.
The incident occurred near uninhabited islands claimed as the Senkaku in Japan and the Diaoyu in China, which sit between Taiwan and Okinawa and have caused diplomatic tensions for decades.
Japan's coast guard said it expelled two Chinese ships as they approached a Japanese fishing vessel sailing in the area.
China's coast guard said separately that it drove out a Japanese fishing boat that "intruded into" waters around the islands.
Relations between Japan and China have worsened since Japanese Prime Minister Sanae Takaichi angered Beijing in November with comments about Taiwan.
Chinese ships last entered waters Japan claims as its territory on June 10, but it is rare for them to approach Japanese fishing boats.
The Japan coast guard said it "issued orders to leave... successfully forcing the Chinese coast guard vessels to leave Japanese territorial waters by approximately 9:20 am (0020 GMT)".
In addition, the coast guard "was deployed around the Japanese fishing vessel to ensure its safety".
China's coast guard (CCG) said in its statement that the "Japanese fishing boat Zuihou Maru intruded into the territorial waters" and that "CCG vessels took necessary measures to warn and expel it".
China and Japan have long accused each other of deploying ships around the islands, sometimes resulting in dangerous standoffs.
The Japanese coast guard said there were four Chinese ships sailing around the area before two entered Japanese waters, saying the action was "a violation of international law".
It said it would "continue to respond calmly and resolutely in accordance with international and domestic law, and will take every possible measure to ensure the security of our territorial waters".
China has also sent boats to other disputed waters in the East China Sea, which is believed to hold possible deposits of energy reserves, despite repeated protests by Japan to stop.
Takaichi said in November that Tokyo could intervene militarily in any attack on self-ruled Taiwan, which China views as its territory and has not ruled out taking by force.
Beijing condemned her comments, and has since urged its citizens against travelling to Japan as well as tightened trade restrictions on some Japanese firms.
