The Battle of Lake Khasan (July 29 – August 11, 1938), also known as the Changkufeng Incident (Russian: Хасанские бои, Chinese and Japanese: 張鼓峰事件; Chinese Pinyin: Zhānggǔfēng Shìjiàn; Japanese Romaji: Chōkohō Jiken) in China and Japan, was an attempted military incursion by Manchukuo (Japanese) into the territory claimed by the Soviet Union. This incursion was founded in the belief of the Japanese side, that the Soviet Union misinterpreted the demarcation of the boundary based on the Treaty of Peking between Imperial Russia and the Qing Dynasty China (and subsequent supplementary agreements on demarcation) and that the demarcation markers were tampered with. Japanese forces occupied the disputed area but withdrew after heavy fighting and a diplomatic settlement.