President Barack Obama's speech to mark the anniversary of 9/11

President Obama has paid tribute to those who died in the 9/11 attacks, at a memorial event at the Pentagon, saying America's greatest weapon was to stay true to itself.

He spoke amid controversy over plans for an Islamic centre near Ground Zero and a threat to burn the Koran.

America would never be at war with Islam, Mr Obama declared.

"We will not sacrifice the liberties we cherish or hunker down behind walls of suspicion and mistrust," he said.