In July 1918 , against the advice of the United States Department of War , President Wilson agreed to send 5,000 US troops as the American North Russia Expeditionary Force ( aka the Polar Bear Expedition ) and 10,000 US troops as the American Expeditionary Force Siberia .
The U.S. sent two groups of soldiers : 5,000 soldiers were the American North Russia Expeditionary Force ( nicknamed the Polar Bear Expedition ) ; and 10,000 were called the American Expeditionary Force Siberia .