Zhang Zuolin
The Soviet Union, determined to retake the Chinese Eastern Railway and recover their influence in China, threatened Zhang Zuolin that they would recognize other warlords. The Soviets reached out to Zhang Zuolin in 1920 and 1921 in order to discuss Mongolia and the Chinese Eastern Railway, but Zhang maintained that he wanted to retake Outer Mongolia as soon as he could. In September 1924, an agreement was reached, in which Zhang agreed to recognize the Soviets and give them control over the railway in return for the Soviets withholding their plans for Outer Mongolia and subversive activities in China.