Afghanistan

There are two schools of thought on withdrawing US troops from Afghanistan. One is that Al-Qaeda has been dispersed and the threat is no longer localized in Afghanistan, so keeping troops there is not an effective use of the military's resources. Moreover, in removing troops from Afghan soil, the Taliban may find less local support making common cause against the invading infidel.  The other is that the Taliban remain a threat to the Afghan government and without an American presence they may will retake control of the country. The modernizing reforms achieved since the US occupation began would be rescinded and the country would revert to the oppressive values the Taliban espouse. 

Where one comes down on this probably hinges on whether one sees the US' role in the world providing a policing presence or as exporting its values (or for some people, neither).  If one sees the US' role only as policing or simply defending the homeland then the troop withdrawal is the obvious answer. If one still sees the US' role as exporting its values, then it should have stayed. 

That Biden chose to leave suggests either that a more inwardly focused perspective is taking hold here (some would characterize it as the "America First" position) or that there has finally been a realization that imposing values on another sovereign nation with a completely different culture and history is harder than it looks. It requires a sustained, often heavy-handed presence which those being "asked" to reform might justifiably see as colonization.