It's hard to fathom the threat to national security hidden in the files of Vietnam War-era Joint Chiefs of Staff Chairman Earle Wheeler. Or records of U.S.-Chilean relations from 1963. Or State Department planning policy from 1947 through 1953.

Yet the federal government is still withholding these records, 20 years after journalists and researchers asked for them under the Freedom of Information Act.

These and other records are among the 10 oldest pending FOIA requests in the federal government. The agency handling those requests, made from 1993 to 1995, is the National Archives and Records Administration (NARA). But that agency isn't the problem.

Instead, it's the State Department, the Pentagon and other bureaucracies that have dragged their feet in declassifying, or removing the "secret" label, from records that long ago lost any real sensitivity. The National Archives can't make them public without those declassifications.

Eight of the 10 oldest requests were made by the National Security Archive, a nonprofit research organization housed at George Washington University. The archive is dedicated to bringing light to the most secretive activities of the federal government. And in the process, the organization has helped change the landscape of open government for the better.

Celebrating its 30th anniversary this year, the National Security Archive has peeled back the curtain on the inner workings of U.S. foreign policy in some of its most contentious episodes: the Vietnam War, the Iran-Contra scandal, responses to ethnic cleansing and genocide in Rwanda and Bosnia, the war on terrorism and many others.

To do so, the organization has filed more than 55,000 FOIA requests, sometimes waiting and appealing for years, and occasionally filing lawsuits, said its director, Tom Blanton. Blanton confessed a kind of love-hate relationship with FOIA: It consistently allows important revelations, but "neither we nor anybody else who is receiving stuff would say the process works very well."

"After 40 or 50 years, most of these files ought to have been declassified," Blanton said. But the system is best compared to clogged arteries.

The idea of making the 10 oldest FOIA requests a matter of public record was the National Security Archives' idea and became law in 2007, Blanton said. "When you've got 20-year-old requests, that tells you the system is not working," he said.

Sept. 26 will mark the 20th anniversary of Robert Parry's request for memos and journal entries regarding Gen. Colin Powell's actions and views on Iran and Central America in the mid-1980s. When I contacted him last week, Parry, a Washington-based journalist who founded consortiumnews.com, didn't remember exactly why he asked for it but said the federal government's reluctance to hand it over was typical.

"The government maintains rather ridiculous levels of secrecy on much of what is held back from the public," he said.

The oldest pending request, dated Aug. 31, 1993, seeks a large number of memos written in 1968 and involving Wheeler, the Vietnam War-era Joint Chiefs chairman.

The NARA said the National Security Archive had received all but 600 of the 12,360 pages that it requested.

"Accordingly, while this request remains open after more than 20 years, the vast majority of the records have already been processed and either made available to the requester or withheld from release under a FOIA exemption," Laura Diachenko, with NARA public affairs, said in an e-mail in May.

The logjam may be breaking on the Wheeler records, however. In May, USA Today reported on a newly released 1969 memo from Wheeler that accused President Richard Nixon of succumbing to political pressure and jeopardizing national security by returning Okinawa Island to Japan.

"Top secret" is stamped all over the memo, but it's been crossed out. Still, there's a big white box on the page blanking out portions of Wheeler's memo that, after 46 years and eight presidential administrations, the public still isn't allowed to see.

Contact James Eli Shiffer at james.shiffer@startribune.com or 612-673-4116. Read his blog at startribune.com/fulldisclosure.