Japan and China have accused each other's air forces of "dangerous" behavior over disputed waters in the East China Sea.
China's Defense Ministry said a Japanese surveillance plane and another plane entered the defense zone Saturday during a joint military drill with the Chinese and Russian navies.
A ministry statement condemned the Japanese move and demanded that the country "stop all reconnaissance and interference activities, or Japan would be solely responsible for all consequences."'
A Japanese Defense Ministry spokesman said a Chinese fighter jet flew close to a Japanese surveillance plane where the countries' air defense identification zones overlap. The ministry also said a second Chinese warplane flew close to a Japanese electronic intelligence aircraft in the same area.
Japanese Defense Minister Itsunori Onodera responded by calling the Chinese actions "outrageous."
Chinese government ships and planes have periodically entered waters near the Senkaku islands, which Beijing also claims and calls the Diaoyus.
Japan's defense minister accused Beijing of going "over the top" in its approach to disputed territory.
Tensions have been running high between China and its neighbors over Beijing's assertive stance on claiming land and sea territory.
Some information for this report provided by Reuters and AP.