Japan's National Police Agency (NPA) convened a meeting on Monday over the incident in which an active-duty Self-Defense Forces officer forcibly entered the Chinese Embassy in Japan.

NPA Commissioner General Yoshinobu Kusunoki said at the meeting that the incident "should not have happened" and described it as "extremely unusual and serious."

Kusunoki stressed the need to prevent similar incidents from occurring again and called for thorough strengthening of security measures to protect diplomatic missions.

About 70 senior police officers from 12 prefectures that host foreign embassies and consulates attended the meeting.

Kodai Murata, a 23-year-old second lieutenant in the Japan Ground Self-Defense Force, allegedly scaled a wall and broke into the Chinese embassy in Tokyo while carrying a knife on March 24.

The Japanese government has so far only described the incident as "regrettable," drawing widespread criticism within Japan.