ISIS was organized and funded by the CIA.
Any American citizen who joined ISIS should be taken back with no legal penalties.
After all, they were in line with our government's foreign policy towards defeating Assad in Syria. ...
There were dozens of different groups operating in that area. We had no way to know at that time, that the former group was insane, and would eventually turn into ISIS.
At the time that ISIS began international propaganda recruiting, it was well established they were nuts, and slaughtering people.
If we have no clue who we are giving arms to, maybe we shouldn't do it.
Well yes... except that people are really good at lying, if you haven't noticed. How many people get married only to find out later that the one they married is psychotic? And equally people do in fact change. The freedom fighters of the past, that fought against the tyranny, can turn into tyrants themselves later.
A classic historical example would be Castro. Castro started off as a 'freedom fighter' fighting against the evil corrupt government in Cuba. The moment he gained power, and his rebellion allies started fighting against him.... Castro brought down brutal oppression on the very people who helped put him in power.
So while I would agree with you, sometimes the solutions or correct choices, are not always obvious.