The United States flew a large number of fighter jets late last month above an area in the East China Sea that Japan and China dispute, Japanese government sources said.
In an extremely rare development, some of the US fighters neared the Chinese mainland by going beyond a Tokyo-proposed median line separating the exclusive economic zones of Japan and China, the sources said.
China scrambled its fighters in response, warning the US side that provocative acts would face counter-attack.
The operation lasted for about a week from June 24, the sources said on Monday.
