People across the United States have paused to remember the victims of 9/11 on the 20th anniversary of the terrorist outrage.
Joe Biden joined former presidents Barack Obama and Bill Clinton at a memorial event in New York City, 20 years to the day since the Twin Towers fell.
The anniversary arrives under the shadow of the coronavirus pandemic and the US withdrawal from Afghanistan – now ruled by the same militants who gave safe haven to the 9/11 plotters.
The US attacks killed nearly 3,000 people and marked the start of a new era of fear, war, politics, patriotism and tragedy.
In a video released on Friday night, Mr Biden mourned the ongoing losses of 9/11.
“Children have grown up without parents, and parents have suffered without children,” said Mr Biden, whose childhood friend is the father of a September 11 victim, Davis Grier Sezna Jr.
But the president also underlined what he called the “central lesson” of September 11: “That at our most vulnerable … unity is our greatest strength.”