This story has been updated.

The watchdog charged with overseeing U.S. spending in Afghanistan says the Pentagon is dodging his inquiries about an $800 million program that was supposed to energize the Afghan economy.

John Sopko, the Special Inspector General for Afghanistan Reconstruction, said the military is restricting access to some documents in violation of law and has claimed there are no Defense Department personnel who can answer questions about the Task Force for Business Stability Operations, or TFBSO, which operated for five years.

“Frankly, I find it both shocking and incredible that DOD asserts that it no longer has any knowledge about TFBSO, an $800 million program that reported directly to the Office of the Secretary of Defense and only shut down a little over six months ago,” Sopko wrote in a letter to Secretary of Defense Ash Carter released today.

The Pentagon’s claims are particularly surprising since Joseph Catalino, the former acting director of the task force who was with the program for two years, is still employed by the Pentagon as Senior Advisor for Special Operations and Combating Terrorism.

In June, the DOD wrote in an official response to Sopko that it “no longer possess[es] the personnel expertise to address these questions,” a point the Pentagon reiterated in October. However, in response to questions from ProPublica Friday, a Pentagon spokesman said in an email that Catalino will be made available for questions. SIGAR had previously spoken to him before the task force shut down in March.

The Pentagon has also refused to allow SIGAR to freely review all the task force documents. Normally the inspector general is simply given the documents it requests, but the Pentagon is insisting that anything related to the task force be read in a DOD-controlled room on DOD computers, and any documents SIGAR wishes to take must first be reviewed and redacted by the Pentagon.

“We have established a reading room at the task force document storage facility specifically for SIGAR use,” said Army Lt. Col. Joe Sowers, a Department of Defense spokesman, in his email.

These “appropriate security safeguards,” as Principal Deputy Under Secretary Brian McKeon called them in a letter to Sopko, “are necessary due to SIGAR’s actions that revealed Personally Identifiable Information [PII] in an unrelated incident.”

The incident McKeon referenced involved information requested by ProPublica under a Freedom of Information Act request last November. ProPublica sought the Commander’s Emergency Response Program database from Afghanistan, which documents how commanders spent money on local projects. SIGAR provided the database, but did not redact names of military personnel, which the Pentagon said should have been done. ProPublica used the database to create an interactive that allows readers to search and sort how the troops spent $2 billion in petty cash.

ProPublica has been analyzing how the Pentagon spent money in Afghanistan, closely tracking waste, such as this $25-million headquarters that no one needed and was never used.

In SIGAR’s report, Sopko said he didn’t buy the Pentagon’s reasoning for not cooperating. SIGAR has refused to abide by the Pentagon’s terms because it believes the law does not allow for them.

“SIGAR believes this vague accusation is a red herring intended to divert attention from DOD’s continued refusal to answer any questions related to TFBSO activities,” the report says. “For example, in response to SIGAR audits and investigations of other matters, DOD has continued to provide unrestricted information and unfettered access requested by SIGAR auditors and investigators.”

But in a follow-up email, Sowers said that the Defense Department’s general counsel said that it “would expect same ground rules for future requests for unclassified docs containing [personally identifiable information] or other sensitive FOIA exempt info.” A SIGAR spokesman said today that the inspector general would wait to comment until officially informed of the broader change in policy.

Despite the Pentagon’s restrictions, SIGAR has documented serious problems with at least one chunk of the $800 million tab. The task force spent nearly $43 million to build a compressed natural gas station in Afghanistan with the hopes of helping the country develop its natural resources and become less dependent on foreign fuel imports. The single station was intended as a model that would be replicated in other areas of the country.

The project, SIGAR found, was ill-conceived from start to finish. Were a similar station built in neighboring Pakistan, SIGAR noted, it would cost about $300,000. The task force spent 140 times that. Even factoring in the extra security costs to build in Afghanistan, “this level of expenditure appears gratuitous and extreme,” SIGAR wrote.

Cost aside, military planners also failed to account for Afghanistan’s lack of a viable local infrastructure to move the natural gas and for the hundreds of millions it would take to build one, SIGAR said.

On an even more prosaic level, the task force forgot to account for one more key item: customers. Besides the 120 cars the United States paid to convert to natural gas, most Afghans have no use for the station. That’s because it costs at least $700 in Afghanistan to convert a car from gasoline to natural gas — more than an average Afghan makes in a year.

SIGAR’s report has generated outrage among some members of Congress who are unhappy not only about the $43-million gas station, but the Pentagon’s lack of cooperation.

“This is shocking in multiple ways. The cost of an unnecessary gas station in Afghanistan skyrocketed to a ridiculous height. Now, the Department of Defense is blocking access to documents and personnel that would shed light on how the money was spent” said Sen. Chuck Grassley, R-Iowa, in a statement. “The lack of accountability and transparency is disgraceful.”