A declassified U.S. Government documentary history of the momentous 1953 coup in Iran, in which Central Intelligence Agency personnel participated, had been the object of widespread demand from historians and others for decades. In recent years, it finally seemed to be on the verge of publication.

But now its release has been postponed indefinitely.

Last year, “the Department of State did not permit publication of the long-delayed Iran Retrospective volume because it judged the political environment too sensitive,” according to a new annual report from the State Department Historical Advisory Committee (HAC). “The HAC was severely disappointed.”

“The HAC was unsuccessful in its efforts to meet with [then-]Secretary Kerry to discuss the volume, and now there is no timetable for its release,” the new report stated.

The controversy originally arose in 1989 when the State Department published its official history of US foreign relations with Iran that somehow made no mention of the 1953 CIA covert action against the Mossadeq government, triggering protests and ridicule.

That lapse led to enactment of a 1992 statute requiring the Foreign Relations of the United States series to present a “thorough, accurate, and reliable” documentary history of US foreign policy. The State Department also agreed to prepare a supplemental retrospective volume on Iran to correct the record. The retrospective volume is what now appears to be out of reach.

In truth, a fair amount of documentation related to the events of 1953 in Iran has been declassified and released. It is unclear how much more of significance remains to be disclosed. (Those who have read the missing volume say there is at least some new substance to it.)

But the position taken by the Obama State Department that 60 year old policy documents are too politically sensitive to be released is disheartening in any case.

Instead of disrupting relations with Iran, which are already fraught, an honest official U.S. account of events in 1953 might actually have elicited a constructive response. But that argument, advanced by the Historical Advisory Committee and its Chairman, Prof. Richard H. Immerman, did not get the serious consideration it deserved.

More broadly, the new annual report of the HAC did identify a few bright spots. One volume of the Foreign Relations series that was released last year met the statutory deadline for publication within 30 years of the events it describes. That hasn’t happened for two decades.

Overall, however, “the declassification environment is discouraging,” the HAC report found.