“Never eat anything larger than your head” – B. Chast.
More to the point, taking over a sovereign nation is difficult at best… and much harder if the current residents are armed and knowledgeable about how to use guerilla tactics… and particularly if some of them are already a militia. And then, much harder again if they’re already radicalized or/and perfectly willing to kill or die for their cause. This is why I always cringe whenever the US sends armed force into that region: It’s a lose, lose, lose proposition. Though some people get richer.