在一九三十年代初期開始的盛世才―蘇聯友好合作期間,蘇聯勢力控制了新疆。1942年盛世才反蘇後,蘇聯被迫從新疆退出。四十年代中期的國際形勢和新疆民族矛盾的激化給蘇聯再次介入新疆事務提供了良好機會。1944年新疆伊犁穆斯林民族在蘇聯幫助下發動了反漢暴動。爲準備暴動,激烈反漢的回族人士在阿拉木圖成立突厥民族解放委員會,全力對新疆進行泛突厥主義和泛伊斯蘭主義宣傳,並同時在蘇聯境內從事軍事人員訓練。不久之後,他們在蘇聯的策動下,又在新疆成立了所謂「解放」組織,利用宗教展開反漢宣傳,並通過親蘇穆斯林控制了阿勒泰地區的反盛世才哈薩克武裝。1944年11月,在盛世才去職離新,國民政府勢力剛剛進入新疆的時候,伊寧事件爆發,東土耳其斯坦共和國成立。1945年1月,雅爾達會議前夕,暴動者在蘇聯軍事人員的幫助下,攻取了國民黨駐軍在伊寧的最後據點。隨後,蘇聯人員領導的伊犁民族軍成立。中蘇友好條約談判前夕,民族軍在蘇聯軍事人員的直接參與和指揮下,向國民黨新疆駐軍全線出擊,並於全面占領伊犁、塔城、阿勒泰三區之後,也就是國民政府和蘇聯簽訂中蘇友好條約後不久,在迪化附近的瑪納斯河畔停火並與國民政府展聞談判。隨後三區與國民黨方面建立了新疆省聯合政府。蘇聯利用新疆問題迫使中國政府接受雅爾達協定,進而簽署中蘇友好條約,把三區,連同外蒙和東北一起,納入蘇聯的勢力範圍。
Soviet influence dominated events in Xinjiang from 1934 to 1942, when Sheng Shicai shifted his allegiance from the Soviet Union to the Guomindang (GMD). During the period of 1944-1945, however, the international situation and the tense ethnic relations in Xinjiang provided the Soviet Union with a good opportunity to re-enter Xinjiang. In 1944 the Moslems in Yili rose in rebellion, which the Soviets encouraged and supported. In order to prepare for the rebellion, the Turkish People's Liberation Committee was established in Alma-Ata. Anti-Han propaganda and military training for people from Xinjiang were carried out on Soviet soil. Within Xinjiang, the Soviets helped the Moslems to establish underground organisations and to smuggle weapons from the Soviet Union. Through the pro-Russian Moslems, the Soviets successfully brought the anti-Sheng Kazak forces in Ashan under their control. In November 1944, when Sheng Shicai was transferred to Chongqing and the new Xinjiang government had not yet established itself, the Yili Rebellion erupted, followed by the inauguration of the Eastern Turkestan Republic. On the eve of the Yalta conference, the rebels, with the assistance of the Soviet Union, cleared the Yili Districts of the GMD troops. Soon after, the Soviet-oriented Yili National Army (YNA) was established. On the eve of negotiating the Sino-Soviet (Chongqing-Moscow) Treaty of 1945, the YNA, with the participation of the Soviet personnel, launched attacks on the Tacheng and Ashan Districts. Shortly after the signing of the Treaty, the YNA occupied Yili, Tacheng and Ashan, and started negotiating with the GMD authorities. As a result, a Xinjiang Coalition Government was established. The Three Districts, however, did not give up their de facto independence until 1949. The Yili Rebellion represented the peak of Soviet involvement in Xinjiang affairs. The Rebellion and the events following it were closely associated with the Soviet Union's Far Eastern policy. Unlike the period of the Sheng-Soviet cooperation of 1934-1942, during which Soviet involvement was vivid and obvious, Moscow's interference in Xinjiang's affairs during the 1940s was masked. Between the Teheran Conference of 1943 and the Yalta Agreement of 1945, the Soviet Union adjusted its East Asia policy and successfully re-established itself in the region. During this period, Stalin used Xinjiang as a bargaining chip in realising his goals of re-gaining all Tsarist-Soviet interests and privileges in East Asia.