Stan, foreign bases are politically sensitive question. Why are bases needed? Just to keep forces in the theatre and this is question of force projection. If you think abut human shield, then you are right of course. At present day the best force projection method is air force. Sometimes the best way is Tomohawk missile. It depends a lot of nature of enemy and georgaphy. I'm waiting the day when US can cover it's allies via this technology.

http://www.defensetech.org/archives/003671.html

You just need to make decision and push the button. No diplomatic discussions about bases (Turkey, Russia, Pakistan etc). You just enforce your will. 1st you just have to wait that enemy will settle in permanent location. Like Russians in Georgia today, this moment.