system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can US/Jordanian forces tell that who they're shooting at is a member of ISIS?
gpt
Educated guesses. 

* If they are waving an ISIS flag, then well, duh. 
* If they attacking known allies (Kurds, etc.), then we assume they are ISIS or an affiliate. 
* If they are attacking a city that we know is not occupied by ISIS, we assume they are ISIS/Affiliate. 
* If they are acting suspicious, armed and not on a friendly list, then we'll probably lump them in as insurgents if we shoot them. 
* If we get a tip and they are armed, we assume ISIS. 

Generally though, if we shoot them, they are ISIS. It saves a lot of paperwork that way. 

Edit: and if they give you gold, we assume they are a friendly, and don't shoot as a way of saying thanks.