I am old enough to remember when what Biden is attempting now was unserious at best and at worst criminal, a return to the wickedness of Charles Lindbergh and the anti-World War II “America First” movement. But lots of things (elite belief in the efficacy of coronavirus vaccines, for example) have changed since the last administration. Maybe if former President Donald Trump had campaigned on staying in Afghanistan for all eternity, he would have been impeached for not getting every last American home by Thanksgiving 2017. The truth is, though, that even Biden isn’t going to have an easy time getting us out of Afghanistan. Like both of his predecessors, he is about to discover that the Pentagon is used to getting whatever it wants and that the US foreign-policy establishment has decades worth of spurious justifications for keeping American troops in the region indefinitely. While it would be nice to think that the president has enough of a mandate to push through a withdrawal, there are good reasons to remain dubious.