Eight days before the 20th anniversary of the darkest day in New York City history, President Joe Biden honored a promise to the families of Sept. 11’s victims and initiated the impending release of classified documents related to the terrorist attacks.

As it should be: Almost nothing we learn about the Saudis or our own government, no matter how uncomfortable, can justify further obfuscation.

Biden’s executive order — signed Friday as nearly 2,000 9/11 victim family members warned him not to bother showing up at memorial remembrances lest he make good on a campaign promise to declassify many materials — does not guarantee that all information heretofore deemed secret will suddenly be published. Nor does it ensure that if and when it does see the light of day, it won’t be so full of black redaction bars as to be rendered useless.

But it does require Attorney General Merrick Garland and heads of other relevant agencies to review and publicly release documents over the next six months after considering “whether the public interest in disclosure of the information outweighs the damage to the national security that might reasonably be expected from disclosure.”

That alone is significant, given that former presidents George W. Bush, Barack Obama and Donald Trump balked, seeming to put America’s relationship with the Saudi royals before the need to answer still-agonizing questions about how the terrorists, 15 of 19 of whom came from the kingdom, were able to carry out their murderous plans.

In the spring of 2020, months after Trump said he would open FBI files — a pledge that aligned with his oft-stated skepticism of federal intelligence and law enforcement agencies — his attorney general told a federal judge that further disclosures would imperil national security, and that even elaborating on that justification “would reveal information that could cause the very harms my assertion of the state secrets privilege is intended to prevent.”

Biden has it right: Keep hiding anything that might endanger American lives. Make public anything, and we mean anything, that doesn’t get over that high bar.