President Barack Obama has made his first visit to Ground Zero in New York. He laid a wreath in memory of those who were killed in the attacks in September 2001.
The ceremony comes four days after US forces killed al-Qaeda leader Osama Bin Laden in Pakistan the man who was believed to be the mastermind of the 9/11 attacks.
Mr Obama did not make a speech. Commentators said it was a time for reflection and that the administration was sensitive to accusations that the president could be seen to be politicising his visit.
Earlier he met firefighters who had lost 15 colleagues on that September day. The US President told them the killing of Osama Bin Laden sent a message to the world and the country that “when we say we will never forget, we mean what we say”.