I can see how this is a tenuous situation for a lot of people, but I just think he wants the Capital, surrounding area, and the District of Columbia in general to be safe and clean. It is embarrassing in front of the world stage for the current condition. Been at least 10 years since I've been there, but I'll save that story for another time.
It may seem extreme, but again - no one else is doing anything. I really don't see this as a first step in some kind of dictorial U.S. 'take over'
PS: Damn, dictorial is not a word