In Sierra Leone in 1995 - 200 highly trained (white) mercenaries (Executive Outcomes) prevented the Sierra Leone civil war - only until corrupt African governments (and the Clinton Administration) decided to give the job over to “Nigerian peacekeepers” and force the Sierra Leone government to accept the Abidjan Peace Accords.
With that, the government collapsed and all the terror one associates with the Sierra Leone civil war came to the fore.
The only thing the USA needs to do with Haiti is authorize the same for Haiti. I bet the entire country could be controlled with 800 private military contractors
Napoleon’s veterans couldn’t keep it. US Marines of the 1920s couldn’t make a dent in its behavior. What could any such peacekeepers do now that would be different?
To do anything that would make it stick would require a complete crushing of the place with enormous Haitian casualties. Crushing so severe that it would be Romanesque style crushing with a rooting out of Vodou like the Romans rooted out Druidism. Then impose a new culture on the survivors. Anything less means you’ll win a temporary calm but in 20 years you’ll be doing it again. None of that is political feasible. Some things aren’t fixable! Best to wall it off and leave it alone. That’s what the Dominicans did with their half of the island.