Afghanistan, Iran, and Iraq–someone else's problem?

The nuclear saber rattling by Iran and recent violence in Afghanistan and Iraq have underlined how futile it is to save cultures from themselves.  We declared victory in Iraq and pulled out; we should pull out of Afghanistan right now.  In the first case, the ethnic power struggles between Shi'ites, Sunnis, and Kurds is ramping up, recalling Joe Biden's observation that the country should really be three (maybe more?).  All that we fought for there is coming apart.  In the second case, U.S...