Although the US army air corps already had its own insignia (a star design similar to that still used at the start of WW2), when the US joined the allies in WW1, it was decided that they should adopt similar style markings to the British and French, and the Red/Blue/White roundel was adopted.

These decals are scaled to represent 24", 30", 36" and 48" diameter in 1/600 scale. The actual sizes are 1mm, 1.25mm, 1.5mm and 2mm, so these are small decals....