President Joe Biden signed an executive order Friday directing the declassification of certain documents related to the Sept. 11, 2001, terrorist attacks, a supportive gesture to victims’ families who have long sought the records in hopes of implicating the Saudi government.

The order, coming little more than a week before the 20th anniversary of the attacks, is a significant moment in a yearslong tussle between the government and the families over what classified information about the run-up to the attacks could be made public. That conflict was on display last month when some 1,800 relatives, survivors and first responders came out against Biden’s participation in 9/11 memorial events if the documents remained declassified.

“The significant events in question occurred two decades ago or longer, and they concern a tragic moment that continues to resonate in American history and in the lives of so many Americans,” the executive order states. “It is therefore critical to ensure that the United States Government maximizes transparency, relying on classification only when narrowly tailored and necessary.”

The order directs the Justice Department and other executive branch agencies to begin a declassification review and requires that declassified documents be released over the next six months.

Still, the practical impact of the executive order and any new documents it might yield was not immediately clear. Past investigations have outlined ties between Saudi nationals and some of the airplane hijackers, but have not established the government was directly involved.

A long-running lawsuit in federal court in New York alleges that Saudi officials provided significant support to some of the hijackers before the attacks and aims to hold the kingdom accountable. The Saudi government has denied any connection to the attacks.

The families have long asserted that Saudi officials played more of a direct role than the U.S. government has said publicly, citing in part the fact that the first two hijackers to arrive in the U.S. ahead of the attack were welcomed and assisted by a Saudi diplomat. They have long accused the government of stonewalling their demands for documents, and on Thursday, urged the Justice Department’s inspector general to investigate the FBI’s apparent inability to locate a photograph, video and other records they seek.

The Justice Department revealed last month that the FBI had recently concluded an investigation examining certain 9/11 hijackers and potential co-conspirators, and that it would now work to see if it could share information that it had previously determined could not be disclosed.

Under the terms of the executive order, the FBI must complete by Sept. 11 its declassification review of documents from that probe, which it has referred to as the “Subfile Investigation.”

Over the course of the next six months, the order states, the government should review for declassification purposes all interview reports, documents with investigative findings, any phone and banking records, other interview reports and other information seen as potentially relevant to the attacks.