Talibans sneak weapons Past Us?

Why are the Untied States Marines to blame about the taliban aneaking weapons? Its not our country! I don't understand why the US is to blame about their own country being just a shit hole. Afghanistan can support their own problem and deal with the Taliban. In my opinion we need to just get out that crap place and focus on our own land. Everyone in Afghanistan is bred to kill. So lets just let them do their own thing.