President Biden will withdraw all American troops from Afghanistan over the coming months, people familiar with the plans said, completing the military exit by the 20th anniversary of the Sept. 11, 2001, attacks that first drew the United States into its longest war. The decision, which Biden is expected to announce on Wednesday, will keep thousands of U.S. forces in the country beyond the May 1 exit deadline that the Trump administration negotiated last year with the Taliban, according to one person familiar with the matter, who like others spoke on condition of anonymity to describe plans that are not yet public. While the Taliban has vowed to renew attacks on U.S. and NATO personnel if foreign troops are not out by the deadline, it is not clear if the militants will follow through with those threats given Biden’s plan for a phased withdrawal between now and September.