Americans are getting a break from presidential politics on this eleventh anniversary of the 9/11 terrorist attacks.

President Obama and Republican challenger Mitt Romney are suspending negative ads and neither will appear at overtly political events.

The president has scheduled a moment of silence at the White House and a trip to the Pentagon.

"He certainly hopes and knows that Americans across the country will take a moment to reflect upon the events of September 11, 2001, and all that our country has been through together since then," White House press secretary Jay Carney said.

Romney is set to address the National Guard in Nevada.

"On this most somber day, those who would attack us should know that we are united, one nation under God, in our determination to stop them and to stand tall for peace and freedom at home and across the world," Romney said in a statement.

"Today we again extend our most profound gratitude to our brave troops who have gone into battle, some never to return, so that we may live in peace," he said.