What else would you use the Marines for?
Obviously, the Marines have resources: firepower, cops, organic air assets, etc. But if you are going to use them in a political way, the person who does so better have a damn good and iron clad reason. And, that justification would have to have public support.
Well cleaning out the UN Building, for starters.
If only...
Barbary Pirates!
(You know, Muslim slave traders...some things really might just be coming full circle.)