U.S. President Joe Biden pays his respects at a 9/11 memorial outside the Shanksville volunteer fire station, as he and first lady Jill Biden stopped at the fire hall after visiting the nearby site where the hijacked United Airlines Flight 93 plane crashed, on the 20th anniversary of the September 11, 2001 attacks, in Shanksville, Pennsylvania, U.S., September 11, 2021. Biden has repeatedly visited the firehouse over the years since 2001. REUTERS/Jonathan Ernst