importantly for the millions of afghans left behind. >> one enormous military effort over the last 20 years. nick payton walsh, thanks very much. let's go to the white house, cnn's jeremy diamond. jeremy, the president will speak today. what kind of future will he paint for afghanistan? >> reporter: well, listen, president biden left it up to the head of the u.s. central command and to his secretary of state to announce the end of the america's longest war. but today he will certainly have to mark that moment as a moment in history. president biden has talked since he came into office vowing that he would not pass this war on to a fifth commander in chief after becoming the fourth commander in chief to oversee this war. so i think he will certainly talk in broad scopes about what this moment in history means, and why he decided to make that decision. we have heard him defend his decision to withdraw u.s. troops for weeks now. but some questions president biden will have to answer,