TOKYO (AP) — Japan said Wednesday it conveyed regrets to China after authorities confirmed they arrested a Japanese army soldier on suspicion of trespass, a day after China protested over an alleged break-in at its embassy in Tokyo.

The case, the latest point of friction in an escalating spat between Japan and China, surfaced Tuesday after Beijing protested to Tokyo.

An individual who claimed to be a Japan Self-Defense Forces officer scaled the wall and forced his way into the embassy compound on Tuesday morning, Lin Jian, a Chinese Foreign Ministry spokesperson, said in a news conference in Beijing.

The Tokyo police on Wednesday told The Associated Press that they arrested a 23-year-old member of the Ground Self-Defense Force, or Japan's army, in the alleged trespassing into the Chinese embassy on Tuesday.

The GSDF confirmed the suspect is a soldier based at the Camp Ebino, in Japan's southwestern prefecture of Miyazaki, and that officials are “fully cooperating” with police.

Japan's Chief Cabinet Secretary Minoru Kihara said the arrest of an SDF soldier was “extremely regrettable."

Kihara also expressed regret that the alleged trespassing was committed even as Japanese police provided routine security around the Chinese embassy, adding that security has since been reinforced, including by increasing staffing.

Following China's protest and demand for preventive measures, Japan conveyed to China its regret over the case and explained that Japanese ministries will respond appropriately, including by taking preventive measures under relevant international and domestic laws, Kihara said.

The suspect forced his way into the embassy hoping to tell the Chinese ambassador to stop China’s hardline stance on Japan, and said he would kill himself with the knife he was carrying if his demand was rejected, Japanese media quoted police as saying.

Tensions between the two Asian nations have escalated in recent months after Japanese Prime Minister Sanae Takaichi said in November a Chinese military action against Taiwan could constitute “a survival-threatening situation” for Japan requiring the use of force. Beijing, which regards the self-governing island as part of its territory, has since stepped up diplomatic and trade reprisals against Japan.

Japan’s NHK public television said the suspect was detained on the spot and handed over to Tokyo police for further investigation and that nobody was injured.

The man allegedly climbed the embassy wall and a knife was left behind, NHK reported.

“China is deeply shocked by the incident and has lodged solemn representations with the Japanese side, expressing strong protest,” Lin said. “The Japanese side has failed to properly manage and discipline its Self-Defense Forces personnel and has not fulfilled its responsibility to ensure the security of Chinese embassies and consulates and their staff.”

Lin demanded Japan immediately investigate the incident thoroughly, punish the individual involved, provide an explanation to China and take preventive measures.