blue on blue Military
denoting or relating to an attack made by one's own side that accidentally harms one's own forces: blue-on-blue incidents. [from the use of blue to indicate friendly forces in military exercises.]
→ blue
blue on blue Military
denoting or relating to an attack made by one's own side that accidentally harms one's own forces: blue-on-blue incidents. [from the use of blue to indicate friendly forces in military exercises.]
→ blue
Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004