Complex sentence: On August 26,1919, the Karakhan Manifesto was published by the Soviet press, but the document did not contain anything about returning the CER to China without compensation--the Soviets had laid the foundation to double-cross the Chinese.
Split into simpler sentences: On August 26,1919, the Karakhan Manifesto was published by the Soviet press, but the document did not contain anything about returning the CER to China without compensation. The Soviets had laid the foundation to double-cross the Chinese.