11. The Americans grew suspicious of the Japanese in August, 1918
In the summer of 1918 the Japanese landed a force of 70,000 men through Vladivostok and the Manchurian border with Siberia, with their stated intention being the rescue of the Czechoslovak Legion. The size of their force made it evident to General Graves that the Japanese intended to leave behind garrisons as they advanced to the west. When the Japanese made contact with the Legion the combined forces, supported by the British and French, continued toward the Urals, intent on reopening the Eastern Front against the Austro-Hungarian Empire. The Japanese refused to continue further west than Lake Baikal. The Americans, desirous of checking the Japanese, remained behind with them.
The Americans assumed control over large sections of the Trans-Siberian Railroad and established a unit to operate it, often clashing with the Allies over priority of supply. They also frequently clashed with Red partisans and Cossacks in remote areas. During the winter months of 1918-19 the Americans found that they, as with so many foreign invaders in Russian history, were ill-equipped to face the weather prevalent in Siberia. The water in the water-cooled heavy machine guns with which they were equipped froze, making the weapons unable to be fired. The equipment on the Trans-Siberian Railroad was often obsolescent and had been poorly maintained, leading to logistics problems. The presence of the large Japanese force was another problem which plagued General Graves, and he was forced to deploy considerable elements of his force to monitor their activities.