9/11 anniversary: Services held 15 years on
Sept.11, NY: Services are being held across the United States and the world to mark 15 years since the 11 September attacks.
Six moments of silence are being held in New York City, to mark the times four hijacked planes crashed and the two World Trade Center towers fell.
Presidential candidates Donald Trump and Hillary Clinton are expected to attend a ceremony at the rebuilt site.
Ahead of the anniversary, President Obama said it was important to remember America's "core values".
"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," he said in his weekly radio address.
The Oslo Times International News Network