NEW YORK: America commemorated the 15th anniversary of the 9/11 attacks Sunday with emotional services of remembrance in New York, Washington and Pennsylvania to honor those who perished in the world's deadliest terror strikes.

On September 11, 2001, four passenger jets crashed into the Twin Towers in Manhattan, the Pentagon and a field in Shanksville, Pennsylvania — killing nearly 3,000 people and changing the world forever.

This year's anniversary comes with the United States locked in a bruising White House election battle between Hillary Clinton and Donald Trump, who both attended the New York service, although Clinton left early after feeling unwell.

US President Barack Obama urged Americans to embrace the nation's diversity and not to allow “terrorists” to divide the country.

“So instead they try to terrorize, in the hopes that they can stoke enough fear that we turn on each other,” said Obama, who observed a moment of silence Sunday at the Oval Office in honor of the nearly 3,000 people killed that day.