A new twist to blue on blue

According to The Guardian the US is currently arming Sunni dissidents in Iraq. Apparently "Arms, ammunition, body armour and other equipment, as well as cash, pick-up trucks and fuel, have already been handed over in return for promises to turn on al-Qaida and not attack US troops". Whether or not such promises extend to British troops is not clear and frankly from the tone of the article there seems to be a fair amount of scepticism as to whether or not the Sunni dissidents can be relied upon to hold to their promise. American forces already have quite a reputation for so called "Blue on Blue" incidents otherwise known as friendly fire - blue being the friendly forces and red being the enemy forces. I guess this will lead to cases of purple on blue where US forces will be killed and injured by enemy combatants firing bullets supplied by the US. And we wonder why we are so mired in Iraq!