US President Joe Biden has ordered the Justice Department and other agencies to review documents relating to the September 11, 2001 terrorist attacks for possible declassification.
Biden signed an executive order on Friday instructing officials to go through papers from the FBI's investigation.
The agencies will have 180 days to release any documents the review finds would not damage national security.
Biden said in the order that as the 20th anniversary of the attacks approaches, the American people deserve to have a fuller picture of what their government knows about the attacks.
Relatives of the victims of the attacks have been calling for disclosure of the documents, citing suspicions that Saudi Arabian government officials had a role in the attacks.
They say Biden will not be welcomed at the 20-year memorial ceremony this month if he takes no action.
Osama bin Laden, the former leader of international terrorist organization Al-Qaeda and the alleged mastermind of the attacks, was from Saudi Arabia.
Investigations have reportedly found no evidence to suggest the Saudi Arabian government supported Al-Qaeda.