Tokyo and Beijing traded barbs Monday as their diplomatic row showed no signs of abating, following Japan’s report that Chinese warplanes had locked their radar systems on Air Self-Defense Forces fighters over the weekend.

Japan’s top government spokesman slapped down Beijing’s allegations that the ASDF aircraft had “maliciously monitored and harassed” the Chinese military warplanes, saying that the Japanese fighters had maintained a safe distance while performing their mission.

“China’s claim that Self-Defense Forces (SDF) aircraft seriously impeded the safe flight of Chinese aircraft is unfounded,” Chief Cabinet Secretary Minoru Kihara told a news conference Monday morning.