Russia's Defense Ministry has released previously classified information detailing the participation of foreign units alongside the Red Army during World War II.
The most famous foreign unit in the Red Army was the French Normandie-Niemen Regiment of three fighter squadrons, but the documents shed light on the Soviet support for units from Poland, Czechoslovakia, Yugoslavia, as well as other countries.
"Thousands of servicemen and civilians strove to fight Hitler's forces and made their way into the Soviet Union, joining the ranks of the Red Army and reinforcing partisan units," the release said.
Bulgaria, Hungary and Romania had citizens who joined volunteer Red Army units although their governments were allied to Nazi Germany during the war.