They for all intents and purposes invaded Siberia in what became known as the Siberian Intervention. Japan's government deeply feared communism, as it was not only a threat to their colonies in Mainland Asia, and a threat to their power, but also anathema to Japanese society as a whole. A rather large Japanese force moved into Siberia and the Russian Far East, ostensibly to help Entente troops (such as the Czechoslovakian Legion). However, it was viewed (not entirely without merit) by Britain and America that this was a bit of landgrabbing by Japan, who had already annexed Korea and Manchuria, and backed certain White Russian commanders over others (arguably to perhaps form a puppet government similar to that of Manchuko in Manchuria). As such, they applied some pressure on Japan, forcing them to withdraw from Siberia, allowing the Soviet troops to retake Siberia from the White Russian forces there.