In a friendly fire incident, two American A-10 Thunderbolt II aircraft attack British tanks participating in the 2003 invasion of Iraq, killing one soldier.

In military terminology, friendly fire or fratricide is an unintentional attack by allied or neutral forces on friendly troops while attempting to attack enemy or hostile targets. Many NATO militaries refer to these incidents as blue on blue. Examples include misidentifying the target as hostile, cross-fire while engaging an enemy, and long-range ranging errors or inaccuracy. Accidental fire not intended to attack enemy or hostile targets, or deliberate firing on one's own troops for disciplinary reasons, is not called friendly fire, and neither is unintentional harm to civilian or neutral targets, which is sometimes referred to as collateral damage. Training accidents and bloodless incidents also do not qualify as friendly fire in terms of casualty reporting.