President Joe Biden touted the U.S. killings of Osama bin Laden and his successor Ayman al-Zawahiri in a fiery speech commemorating the 9/11 anniversary on Sunday. “We will follow them to the gates of hell,” the president said, echoing remarks he and other U.S. leaders have made in the past. “Our commitment to preventing another attack on the United States doesn’t end,” Biden added to a crowd in front of the Pentagon, where a hijacked American Airlines Flight 77 crashed and killed 189 people. “We’ll continue to monitor and disrupt those terrorist activities wherever they exist, and we’ll never hesitate to do what’s necessary to defend the American people. What was destroyed we have repaired. What was threatened, we fortified. What was attacked, the indomitable spirit has never wavered. To keep touch of the memory, to keep it bright for all the decades to come.” Biden, along with Defense Secretary Lloyd Austin and Joint Chiefs of Staff Mark Milley, appeared at the Pentagon ceremony, while Vice President Kamala Harris paid tribute at the 9/11 Memorial in New York. First Lady Jill Biden appeared in Shanksville, Pennsylvania, to commemorate United Airlines Flight 93.