Sino-Soviet relations remained sour after the conflict, despite the border talks, which began in 1969 and continued inconclusively for a decade. Domestically, the threat of war caused by the border clashes inaugurated a new stage in the Cultural Revolution: China's thorough militarization. The 9th National Congress of the Communist Party of China, held in the aftermath of the Zhenbao incident, confirmed Defense Minister Lin Biao as Mao's heir apparent. Following the events of 1969, the Soviets further increased their forces along the Sino-Soviet border and in the Mongolian People's Republic.