Tokyo (CNN) Japan scrambled warplanes on Thursday after four Chinese coastguard ships and a drone aircraft entered territory it claims around disputed islands in the East China Sea, according to Defense Ministry officials.

Tokyo said it was the first time Beijing has used an unmanned aircraft in the long-simmering dispute over the islands, called the Senkaku by Japan and the Diaoyu by China.

Japanese Defense Minister Tomomi Inada said use of the drone aggravated tensions inflamed by what Japan says are a record number of scrambles by its Self-Defense Force aircraft in response to Chinese incursions in the last fiscal year.

"China is escalating the situation unilaterally, and this is totally unacceptable," Inada said at a press conference.

A picture released by Japanese coast guard shows a drone over a Chinese coast guard ship which Japan says was it its territorial waters

Japan responded with two F-15 fighter jets along with two early warning aircraft, according to the defense minister.

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