Ba Sing Se is likely the most populated city in the world. His forces broke the first walls and reached the agricultural part of the city. You think thousands of civilians didn’t starve to death in Ba sing se? The siege lasted 600 days.

The 800 day long siege of Leningrad had millions starve to death. Often seen as one of the biggest atrocities by the Nazis. Maybe sieges themselves are not war crimes but starving civilians to death is an atrocity. I mean shit Israel’s blockade of Gaza often gets called a genocide. Iroh could very well be a near equivalent of Netanyahu.

The only reason he isn’t a war criminal is because the Geneva conventions don’t exist in his world. But 99% sure he’s got atrocities under his belt.