TOKYO — China says it has protested to Japan over an alleged break-in at the Chinese Embassy in 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.

Tensions between the two Asian nations have escalated in recent months after Japanese Prime Minister Sanae Takaichi said in November a Chinese miltray 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, believed to be a soldier in Japan’s army, or the Ground Self-Defense Force, was detained on the spot and handed over to Tokyo police for further investigation. Nobody was injured, according to the TV report.

The man allegedly climbed the embassy wall and a knife was left behind, NHK reported. TBS television said the suspect carried a SDF identification card. Police are investigating the case as a suspected trespass, Japanese media said.

Tokyo police refused to confirm the report or comment on the case. The Ground Self-Defense Force told The Associated Press it was aware of the report and currently investigating but couldn’t comment on it.

“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.