 These privileges were significant in the Asian strategies of the Soviet Union because Port Arthur and Dalian were ice-free ports for the Soviet Navy, and the China Far East Railway and the South Manchuria Railway were the essential arterial communications which connected Siberia to Port Arthur and Dalian.As Mao Zedong thought that the usage rights of the Chinese Eastern Railway, the South Manchuria Railway, the Port Arthur and Dalian were part of Chinese state sovereignty, he required the Soviet Union to return these interests to China, and this was a crucial part of the Sino-Soviet Treaty of Friendship.Joseph Stalin initially refused this treaty, but finally agreed with this treaty.