President Joe Biden signed an executive order Friday to release classified government documents related to the terrorist attacks on Sept. 11, 2001.

According to the Washington Post, Biden instructed the US attorney general to "personally examine the merits of all cases" where the government had invoked state secrets privilege and "to err on the side of disclosure in cases where, as here, the events in question occurred two decades or longer ago."

The executive order marks a fulfillment of a campaign promise but also a necessary optics move as families of the 9/11 victims have said they did not want Biden to attend any anniversary events, unless he declassifies the documents.

"When I ran for president, I made a commitment to ensuring transparency regarding the declassification of documents on the September 11, 2001 terrorist attacks on America," Biden said in a White House statement. "As we approach the 20th anniversary of that tragic day, I am honoring that commitment."

The families involved sent a letter to the White House in August, indicating that Biden would not be welcome to events, unless they saw action.

Following the letter, the Justice Depart pledged to review some of the Sept. 11 documents, but many saw this as not enough. Now, Biden is taking a step further to review and declassify documents relating to the tragedy from two decades ago.

"My heart continues to be with the 9/11 families who are suffering, and my Administration will continue to engage respectfully with members of this community," Biden said in Friday's press release on the declassification review. "I welcome their voices and insight as we chart a way forward."