The Soviets had very good relations with the KMT (known as the "Nationalists" today, but socialists at the time) for most of the time. Stalin himself personally greenlit Chiang to begin the war against Japan and generously supplied him with weapons (in similar way as he later did with Kim and the attack on South Korea). The war was of course an absolute disaster for China, and included such incidents as the KMT killing over 1 million of Chinese civilians with a manmade flood just to slow the Japanese advance. They only really began supporting Mao after Chiang got very close to the Americans after 1941. And Mao, like Tito, never allowed himself to truly become a Soviet vassal.
The Soviets had very good relations with the KMT (known as the "Nationalists" today, but socialists at the time) for most of the time. Stalin himself personally greenlit Chiang to begin the war against Japan and generously supplied him with weapons (in similar way as he later did with Kim and the attack on South Korea). The war was of course an absolute disaster for China, and included such incidents as the KMT killing over 1 million of Chinese civilians with a manmade flood just to slow the Japanese advance. They only really began supporting Mao after Chiang got very close to the Americans after 1941. And Mao, like Tito, never allowed himself to truly become a Soviet vassal.