Japanese Deputy Chief Cabinet Secretary Koichi Hagiuda said Tuesday, as quoted by The Japan Times, that the country's fighter jets had "never taken any of the provocative actions as claimed" by China’s Defense Ministry.
Locking a fire-control radar onto a jet means that the aircraft is ready to fire a weapon and the pilot in the targeted aircraft has a special system signaling that the aircraft is in danger.
Relations between Japan and China have been strained amid a dispute over uninhabited islands in the East China Sea. The Japanese, who have claimed the islands since the 19th century, call them the Senkaku Islands, the name mostly recognized globally, while in China they are known as the Diaoyu Islands.
In 2014, Japan and China agreed to reduce tensions over the disputed islands. However, Chinese vessels repeatedly sailed into Japanese territorial waters around the Senkaku Islands in 2015.