China's coast guard said it sent vessels to patrol the Senkaku Islands, a territory disputed with Japan.
On the 10th, China's coast guard said on social media that "the coast guard 2503 vessel flotilla patrolled within our Diaoyu Dao (Senkaku) territorial waters," adding, "this is a rights-protection patrol carried out by China's coast guard in accordance with the law."
Japan currently exercises effective control over the area, but China claims sovereignty, and the two countries remain at odds. In particular, patrols by China's coast guard have served as a factor heightening diplomatic and security tensions between China and Japan.
Previously, China had sent coast guard ships to waters near the Senkaku Islands almost daily. When Japan makes remarks or takes actions that infringe on China's so-called "core interests," Beijing discloses the patrols, which is seen as aiming for a kind of show-of-force effect.
Because the announcement came around the same time the Liberal Democratic Party, led by Japan Prime Minister Sanae Takaichi, won a landslide in the House of Representatives election (general election) on the 8th, it is interpreted as the Chinese government sending a warning to the Takaichi Cabinet.
Prime Minister Takaichi suggested possible involvement in November, saying that "a Taiwan contingency could constitute a situation threatening Japan's survival." China immediately pushed back and launched retaliatory steps such as a travel advisory, but this appears to have helped Takaichi sharply boost approval ratings.