Interventionism Always Spreads: Jim Henley discusses whether it would be possible to have a libertarian system at home while being interventionist abroad:

It still looks to me like statism abroad leads to more statism at home. For instance, suppose we not only can "rebuild Afghanistan" (which I doubt), but do. Liberals will then demand "How about some 'nation-building' in our [inner city/distressed agricultural regions/declining industrial areas]?" Conservatives will want to know why we shouldn't insist on the same respect for authority at home as we do in the provinces.

I quite agree. There is no bright line separating the rest of the world from us. "Our actions" there are in fact actions of specific Americans, both here and abroad. Those molding foreigners do not cease to be Americans when they return to the states (or when they step out of their government buildings into the DC burbs). If they are successful in molding foreigners, they will naturally feel that American problems need their touch.

As with all socialism, trying to control anything is like trying to push a balloon intro a certain shape. Every squeeze you make will create a bulge elsewhere; only by completely enclosing the balloon, so that you are controlling all of its surfaces, can you dictate the shape.

People are like that. We resist being molded.