Ms. Clooney should strap on a gun and find them...bring them in.  The only way to eradicate ISIS is to kill them where they are. At this point does Clooney think they will be brought to the Hague?
Better to kill them than waste money on prosecuting them.
The US is tracking many down...and killing them. Eventually when they are absolutely on their knees then those remaining will have a better chance of being caught.
Clooney is just grand standing with her talk. It is great when you are married to a celebrity then you can get away with saying things that really don't make sense.  How many heard of her before she married George Clooney?
We all know the UN will not go and find them.  Too many countries involved  with different agendas.