The reason cited for the attack was to support China's ally, the Khmer Rouge of Cambodia, in addition to the mistreatment of Vietnam's ethnic Chinese minority and the Vietnamese occupation of the Spratly Islands which were claimed by China. To prevent Soviet intervention on Vietnam's behalf, Deng warned Moscow the next day that China was prepared for a full-scale war against the Soviet Union; in preparation for this conflict, China put all of its troops along the Sino-Soviet border on an emergency war alert, set up a new military command in Xinjiang, and even evacuated an estimated 300,000 civilians from the Sino-Soviet border. In addition, the bulk of China's active forces (as many as one-and-a-half million troops) were stationed along China's border with the Soviet Union.