The Browning .50 caliber machine gun has been used as a vehicle weapon and for aircraft by the United States from the 1920s to the present day. It was used during World War II, the Korean War, the Vietnam War, as well as during operations in Iraq in the 1990s and 2000s. It is the primary heavy machine gun of NATO countries, and has been used by many other countries. It is still in use today, with only a few modern improvements. Right now, it is the longest serving machine gun in the US military.