The Allied bombing of Yugoslavia in World War II involved air attacks on cities and towns in the Kingdom of Yugoslavia by the United States Army Air Force (USAAF) and Royal Air Force (RAF), including the Balkan Air Force (BAF), between 1941 and 1945, during which period the entire country was occupied by the Axis powers. Dozens of Yugoslav cities and towns were bombed, many repeatedly. These attacks included intensive air support for Yugoslav Partisan operations in May–June 1944, and a bombing campaign against transport infrastructure in September 1944 as the German Wehrmacht withdrew from Greece and Yugoslavia. This latter operation was known as Operation Ratweek. Some of the attacks caused significant civilian casualties.