The meaning of "friendly fire" hasn"t changed, Jim, but it's not precise enough for modern First World war-fighting.

Operations analysis (the study of what worked and what went wrong in military operations) has an experimental aspect called "war gaming", in which aspects of a conflict are played out in a group thought experiment. In these sessions, the main parties to the conflict are designated Blue (us), and Red (them -- the enemy). For the history buffs in our midst, this technique became popular during the Cold War.

But the post-Cold War world is full of conflicts whose complexities are openly acknowledged. In a counter-insurgency operation, such as the continuing Thing in Afghanistan, there are at least three sides: the "coalition forces" (aka ISAF and the Americans), the Government of the Islamic Republic of Afghanistan, and "insurgents" of various stripes, such as the Taliban. So the war-gamers had to account for the people who are in the war but are not Us (a First World Superpower and its allies) or Them (the clear and present danger to the First World Superpower, aka The Enemy). In Afghanistan, that actor is the national government, so the war-gamers chose Green to represent the Afghan national security forces, both army and police.

So, nowadays, in a news story about Afghan police officers turning their weapons on American soldiers, you will see the phrase "green-on-blue attack". In 2002, when a USAF pilot strafed a Canadian infantry battalion on exercise at the Tarnak Farm training area near Kandahar City, it was a "blue-on-blue" incident.

I haven't seen "friendly fire" in years.

"Collateral damage" has likewise gone out of fashion, for (in my opinion) two reasons: first, it is often difficult to identify the intended target of an attack, especially when it is an IED strike, and, second, because the acknowledged target of an attack is a civilian and others who die in the fire-fight or drone strike are assumed to be that person's henchmen.

For example, in 2009 a massive IED blew up a bus in Kandahar City, killing everyone aboard and many passers-by, and wounding lots more; the butcher's bill came to more than 150 casualties. There were no military installations nearby, and the road where the IED was laid was not part of a convoy route. Eventually, intelligence analysts concluded that the IED blast was part of a long-running war between commercial factions over government contracts, but the intended target was never identified. Perhaps the road surface itself was the target -- a big enough hole, and everybody with a dump-truck and half a dozen shovels could get a piece of the repair action.

See the problem? Events like that produce the weird jargon of today, and retire the weird jargon of yesterday.