President Clinton is expected today to extend the deadline for declassification of historically significant documents by 18 months from April 2000 to October 2001 because executive branch agencies are behind schedule and still have hundreds of millions of pages to review.

A White House official called Clinton's 1995 executive order mandating the automatic declassification of all 25-year-old documents "an unprecedented achievement" that to date has made more than 670 million pages of government documents available to the public. But without an extension, he said, the CIA, State Department, Pentagon and other agencies could have been forced to release sensitive national security information in April without adequate review of the documents.

While such a release would clearly speed the process, it could also incur the wrath of Congress and trigger legislation shutting the program down, according to Steven Garfinkel, director of the National Archives' Information Security Oversight Office.

Tom Blanton, director of the nonprofit National Security Archive at George Washington University, said the deadline extension shows "that some agencies had leadership and will, and some agencies dragged their feet--and are now being rewarded."

Blanton said he would not object to extending the deadline "if the White House issued the equivalent of an inspector general's report to see why agencies like the CIA have been unwilling to meet the demands of the order. That hasn't happened, and the net effect has been to reward the slackards."

FORESEEING THE FALL: The CIA's failure to foresee the fall of the Soviet Union has been trumpeted so long and loud in some quarters that it's become an article of faith among agency bashers. CIA officials say there's only one thing wrong with the allegation: It isn't true.

And now they're hoping to lay it to rest, once and for all, during a three-day conference on "U.S. Intelligence and the End of the Cold War" that began yesterday at Texas A&M University's Bush School of Government and Public Service.

"The assertions that CIA got it blatantly wrong are unfounded," said Lloyd D. Salvetti, director of the CIA's Center for the Study of Intelligence, which is co-sponsoring the conference.

The agency's evidence: a 378-page volume of 24 intelligence estimates on the Soviet Union from 1988 to 1991--declassified for the conference.

"You do not have to take our word in defense of our judgment to see how well we did," said Salvetti. "Reach your own conclusions."

One document, from September 1989, is entitled "Gorbachev's Domestic Gambles and Instability in the USSR." It begins:

"[Soviet President Mikhail] Gorbachev and other Soviet leaders are concerned about serious future breakdowns of public order in the USSR. This concern is well justified. The unrest that has punctuated Gorbachev's rule is not a transient phenomenon. Conditions are likely to lead in the foreseeable future to continuing crises and instability on an even larger scale--in the form of mass demonstrations, strikes, violence, and perhaps even the localized emergence of parallel centers of power."

Jeffrey T. Richelson, an intelligence expert, has reached his own conclusion on the basis of previously declassified information. His verdict: not guilty.

"I think they did a good job," Richelson said. "If you had read the estimates and studies that I read from 1985 to May of 1991, I don't think anybody would have been surprised by the evolution of events in the Soviet Union, and that's all that anybody could ask."

Whence, then, this pervasive sense that the agency missed the biggest news event that ever occurred on its watch?

"Partly it comes from statements by [Sen. Daniel Patrick] Moynihan [D-N.Y.] and partly it comes from the assumption that, because we didn't announce all of this was going to happen, there was no understanding that it could," Richelson said.

PICTURE THIS: Director of Central Intelligence George J. Tenet may have suspended the security clearance of his predecessor, John M. Deutch, in August for violating government rules by working with classified material on an unsecured computer at his home, but, hey, no hard feelings.

Deutch's portrait recently went up in the main first floor corridor at agency headquarters with all the other DCIs, except that of Richard M. Helms. Helms's portrait has been hanging in Tenet's personal dining room for more than a year.

Vernon Loeb's e-mail address is loebv@washpost.com