Agreement? Never happened.
Sadam Hussein? IRGC? United States?
When?
It's never happened. The US itself doesn't abide by Geneva convention. Let alone other UN members.
You're living in pretense, I'm sorry to point out.
The world is run by terrorists. The only question is which terror group you want to retain power.
Personally, I like the multiculturalism that the US champions, and the Turks used to, and the Khan dynasty used to, and Persia used to. And only because it's the most likely recipe for the longest track record for peace.
Like it or not, history doesn't agree with your optimism as much as you and I wish it did.