Politics is threatening to overshadow the ninth anniversary of the September 11 attacks today.
Families of more than 2,700 people killed at the World Trade Centre will mourn their loved ones by reading their names at an anniversary ceremony this morning.
US President Barack Obama and first lady Michelle Obama plan to attend separate memorial services at the Pentagon and at Shanksville, Pennsylvania, where more than 200 others were killed in the 2001 attacks.
But a debate over a planned mosque near ground zero that has polarised the nation could mar the ceremonies.
Thousands are expected at protests both for and against the proposed Islamic centre and mosque north of ground zero.
Some victims' family members are torn about whether to engage in a political rally on the anniversary of their loved ones' deaths.
Further controversy came after the pastor of a small American church planned to burn copies of the Koran to mark the 9/11 anniversary.
The Rev Terry Jones later announced he would cancel the plans, but then said he is reconsidering and is believed to have flown into New York last night.
Earlier, Mr Jones' son, Luke, said the Koran-burning event will not take place today but could not say whether there would be a future event.
The book burning plans have sparked violent protests in Afghanistan.
A demonstration today in Puli Alam, the capital of the eastern Logar province, turned ugly with protesters chanting "death to America" and setting shops and police checkpoints on fire.
Officials said at least 11 people were injured in similar protests across Afghanistan on Friday.