Former US President George W. Bush has called for his nation to reunite in a powerful speech delivered on the 20th anniversary of the September 11 terrorist attacks.
Bush told people at the Flight 93 National Memorial in Pennsylvania that Americans learned much about themselves on September 11.
"We learned that bravery is more common than we imagined, emerging with sudden splendor in the face of death," Bush said at a ceremony.
Bush, who was president during the attacks, commended the courage of the Flight 93 passengers and crew who are believed to have foiled an attack on the US Capitol by leading the plane to crash in rural Pennsylvania.
"The 33 passengers and seven crew of Flight 93 could have been any group of citizens selected by fate. In a sense, they stood in for us all," Bush said.
"The terrorists soon discovered that a random group of Americans is an exceptional group of people."
He encouraged Americans to put aside their political differences in the spirit of what he saw after 9/11.
"In the weeks and months following the 9/11 attacks, I was proud to lead an amazing, resilient, united people.
"When it comes to the unity of America, those days seem distant from our own malign force, seems at work in our common life that turns every disagreement into an argument and every argument into a clash of cultures.
"So much of our politics has become a naked appeal to anger, fear and resentment that leaves us worried about our nation and our future together."
Bush said it was time to come together.
"I come without explanations or solutions. I can only tell you what I've seen. On America's day of trial and grief, I saw millions of people instinctively grab for a neighbour's hand and rally to the cause of one another. That is the America I know.
"At a time when religious bigotry might have flowed freely, I saw Americans reject prejudice and embrace people of Muslim faith. That is the nation I know.
"At a time when nativism could have stirred hatred and violence against people perceived as outsiders, I saw America's reaffirm their welcome to immigrants and refugees. That is the nation I know.
"This is not mere nostalgia. It is the truest version of ourselves. It is what we have been and what we can be again.
"Twenty years ago, terrorists chose a random group of Americans on a routine flight to be collateral damage in a spectacular act of terror.
"The 33 passengers and seven crew of Flight 93 could have been any group of citizens selected by fate. In a sense, they stood in for us all."