They do, kinda sorta, but it's a long and arduous process. The Hmong tribesmen from Laos who sided with the US during Vietnam, took some 30 years to get out of refugee camps in Thailand for example. Even before that, the ones evacuated first we're in legal limbo for 15 years, until the US decided to grant them citizenship.Strange, you never see the US taking refugees from the wars that they started/caused.
Is only the 'loyal vassals' that need to clean the mess.
The ability to hide behind two oceans is great to avoid the problem.