Hailing the values and resilience that he says both define and sustains Americans, President Barack Obama on Saturday honoured the nearly 3,000 victims of the September 11, 2001, attacks.
In his weekly radio and internet address, he also hailed the bravery of survivors and the emergency personnel who responded, and the work of scores of others who have worked since to keep the US safe.
"In the face of terrorism, how we respond matters ... We cannot give in to those who would divide us. We cannot react in ways that erode the fabric of our society," he said.
The attackers' goal was to frighten Americans into changing how they live, Obama said, adding: "Americans will never give in to fear."
"We're still the America of heroes who ran into harm's way, of ordinary folks who took down the hijackers, of families who turned their pain into hope," Obama said.
Diversity 'makes us resilient'
"It's our diversity, our welcoming of all talent, our treating of everybody fairly - no matter their race, gender, ethnicity, or faith - that's part of what makes our country great. It's what makes us resilient," said the president, whose term ends in January 2017.
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Nearly 3,000 people were killed in New York City, Pennsylvania and at the Pentagon when hijacked commercial airliners were slammed into all three locations in attacks that were planned and carried out by the al-Qaeda group.
Al-Qaeda leader, Osama bin Laden, was killed nearly a decade later by US forces during a May 2011 raid on his Pakistani hideout that Obama authorised.
Obama noted in his address that the threat has evolved since September 11, 2001, "as we've seen so tragically from Boston to Chattanooga, from San Bernardino to Orlando", cities that suffered headline-grabbing attacks.
He pledged that the US will stay relentless against attacks from al-Qaeda and the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group, which is spreading its mayhem across the Middle East and the West.
"So in Afghanistan, Iraq, Syria and beyond, we'll stay relentless against terrorists like al-Qaeda and ISIL.
"We will destroy them. And we'll keep doing everything in our power to protect our homeland," Obama said.
Obama will mark Sunday's anniversary by observing a moment of silence in the privacy of the White House residence at 8:46am EDT, when American Airlines Flight 11 crashed into the north tower of the World Trade Center, before delivering remarks at a Pentagon memorial service.
Source: Associated Press