Millions of Russians are taking to the streets to celebrate the country's annual Victory Day, marking the Soviet Union’s defeat of Nazi Germany in World War II. The holiday, celebrated every May 9, is entering its 72nd anniversary since the official surrender of Nazis to Joseph Stalin. Although the tradition started under Stalin, the day has become Russia's most important secular holiday. Missile launchers, tanks, and artillery pieces were included in the parade, while military aircrafts flew overhead as a symbol of victory.