[https://edition.cnn.com/2021/09/10/politics/biden-september-11-anniversary-video/index.html](https://edition.cnn.com/2021/09/10/politics/biden-september-11-anniversary-video/index.html) >"President Joe Biden paid tribute to the victims of the September 11 terror attacks in a short video address on Friday, saying ahead of the attacks' 20th anniversary that the "central lesson" of 9/11 is that national unity is America's greatest strength."