This is a listing of the nationality markings used by military aircraft of the United States, including those of the U.S. Air Force, U.S. Navy, U.S. Marine Corps, U.S. Coast Guard, U.S. Army and their predecessors. The Civil Air Patrol is also included for the World War II period because it engaged in combat operations (primarily anti-submarine flights) which its July 1946 charter has since explicitly forbidden. History The first military aviation insignias of the United States include a star used by the US Army Signal Corps Aviation Section, seen during the Pancho Villa punitive expedition, just over a year before American involvement in World War I began. The star was painted only on the vertical tail, in either red (the most often used color) or blue (less likely, due to the strictly orthochromatic photography of that era, rendering the red star as a black one in period photos). At the same time, the US Navy was using a blue anchor on the rudders of its seaplanes. After American entry into World War I As of 19 May 1917 all branches of the military, outside of the Western Front of Europe were to use a circular dark-blue field containing the single, five-pointed regular pentagram-outline white star, symbolic of a U.S. state from the national flag, itself containing a central red circle, painted in the official flag colors. A tricolor roundel was introduced by the US Army Air Service in February 1918 for commonality with the other European Allies, all of whom used similar roundels. American aircraft also used vertically-striped British and French style tricolors on the rudders during World War I, the British and French markings having the blue stripe forward, while American regulations specified that their aircraft have the red stripe forward although some of their aircraft had the colors in the French order. The order of the USAAS roundel's colors were similar to those of the defunct Imperial Russian Air Service. No connection existed between the US roundel and other Allied forces' military aircraft services, beyond the fact that the United States had joined the Allies of World War I and was using a tricolor roundel in what was now an available order. Tsarist aircraft often used a significantly larger white central circle, while the narrower red and blue rings on such large white-centered variant insignia were often separated with additional white rings. From at least as early