The Japanese destroyer sailed through the strait from early morning to late afternoon, according to a statement by a Chinese military spokesperson, who said naval and air forces were deployed to observe the vessel throughout its passage.

Japan’s Self-Defense Forces declined to comment on the transit. The passage comes against the backdrop of heightened regional tensions over Taiwan, which claims as its territory despite opposition from ’s government.

Beijing considers the Taiwan issue a core national interest and frequently characterizes it as a “red line” in diplomatic relations. It also asserts sovereignty over the strait, a key international shipping route, and has responded strongly to foreign naval movements in the area.

China’s foreign ministry spokesperson said at a press briefing that the transit represented a “display of force” and accused Japan of compounding earlier tensions with what he described as “mistakes upon mistakes.” He added that China had lodged formal diplomatic protests with Tokyo.

Relations between the two countries have deteriorated in recent months, particularly after remarks by Japanese Prime Minister suggesting that a potential Chinese attack on Taiwan could trigger a Japanese military response.

China’s military had previously tracked a foreign naval transit through the strait in February, when an Australian warship sailed the same route, according to state-backed media reports. The latest incident underscores persistent friction over freedom of navigation and sovereignty claims in one of Asia’s most strategically sensitive waterways.

An individual claiming to be an active-duty officer of the Japan Self-Defense Forces scaled a wall and entered the Chinese Embassy in Tokyo earlier in the day, Chinese foreign ministry spokesperson Lin Jian said at a regular press briefing.

Lin said the individual admitted the act was illegal and threatened to kill Chinese diplomatic personnel “in the name of God,” prompting what Beijing described as shock and concern over the safety of its staff.

China called on Japan to conduct a thorough investigation, hold those responsible accountable and ensure the security of Chinese embassies and consulates.

JJapan’s defence ministry did not immediately respond to requests for comment regarding the incident or the alleged affiliation of the individual involved.

The incident comes against a backdrop of deteriorating relations between China and Japan. Tensions have risen since Japanese Prime Minister Sanae Takaichi suggested that a potential Chinese attack on Taiwan could prompt a military response from Tokyo.

Japan is also expected to downgrade its description of bilateral ties in an upcoming diplomatic report, citing a series of confrontations over the past year, while Beijing has reiterated calls for Tokyo to withdraw what it views as provocative remarks.