In 1965, in the midst of the Sino-Soviet Split, in order to punish the North Korean regime for its lack of support, China is thought to have demanded that the 160 square kilometers around Paektusan be conceded to it as compensation for the economic and military aid provided by Peking during the Korean War (1950-53)[16] Between March 1968 and March 1969, various military skirmishes took place in the Paektusan region between the North Korean and Chinese armed forces. These were consequences of the tensions caused by the cultural revolution and the savage criticisms made of Kim Il-Sung by the Red Guards. During these years of unrest, Peking closed its border with its neighbor. China abandoned its claim in November 1970, in order to improve relations with Pyongyang. The abandonment of the Chinese claim was preceded by a rapprochement between Peking and Pyongyang from the start of the 1970s. In January, both governments signed a navigation agreement on the Yalu and Tumen rivers.