Will pulling US troops from Afghanistan revive extremist threat?

At its start, America’s war in Afghanistan was about retribution for 9/11. Then it was about shoring up a weak government and its weak army so that Osama bin Laden’s al-Qaida could never again threaten the United States.

Now it’s about over. With bin Laden long since dead and the United States not suffering another major attack, President Joe Biden is promising to end America’s longest war and move on to what he believes are bigger, more consequential challenges posed by a resurgent Russia and a rising China.