A series of solemn ceremonies at Ground Zero in New York, the Pentagon and a crash site in Pennsylvania have marked the ninth anniversary of the terror attacks on 11 September 2001.
In New York, US Vice-President Joseph Biden and New York Mayor Michael Bloomberg were among those attending the annual ritual of reading the names of those killed when two hijacked airliners hit the World Trade Center.
At the Pentagon, President Barack Obama said the US was not at war with Islam, and promised the United States will be defined by hope rather than fear.
Earlier, the Florida pastor behind the threat to burn Korans in Florida said the event had been cancelled permanently.
The pastor, Terry Jones, is in New York, where he says he wants to meet a leading imam to discuss the proposal for an Islamic centre to be located a short distance from Ground Zero.
Later on Saturday, rival protests began close to Ground Zero, by groups opposed to or supporting the building of a controversial centre in the area, the BBC reports.
Hundreds of people attended both demonstrations, which became heated but passed off without violent incident.
Background to Koran controversy
Mr Jones, the pastor of the tiny Dove World Outreach Center in Gainesville, Florida and the author of a book entitled Islam Is of the Devil, had planned to stage an International Burn a Koran Day on Saturday, saying the book was "evil".
The FBI had visited Mr Jones to urge him to reconsider his plans and he was telephoned by US Defence Secretary Robert Gates.
In New Zealand, firefighters took part in a 9/11 commemoration in Christchurch on Saturday.