In the intelligence community, the phrase "sources and methods" is holy writ. It has to do with not disclosing what you know for fear of revealing how you know it. It is a matter of not tipping off a target that you have bugged a telephone, broken a code, or bribed an agent to steal a document.
There have been some classic disputes over protection of sources and methods. In 1975, CIA Director William Colby warned the House Intelligence Committee that disclosure of four words - which he would not identify - in a Middle East intelligence summary would cause irreparable damage.
As it developed, the four words had to do with Egyptian tanks observing radio silence as they prepared in 1973 for the Yom Kippur invasion of Israel. That led to the eventual disclosure that the CIA had a listening post in Jordan, courtesy of King Hussein, who, it later emerged, was on the agency's payroll.
A real sources and methods problem!
But, in recent times, "sources and methods" has become something of a briefing official's mantra, trotted out as an all-purpose justification for withholding information in the war on terrorism. Most recently, it was invoked by the White House last weekend before the administration decided to release the dramatic 40 minutes of videotape of Osama bin Laden gloating about the greater-than-expected success of the Sept. 11 hijackings.
It was hard to understand why the administration would delay dissemination of evidence against Mr. bin Laden that is about as close as one gets to a smoking gun. But Vice President Dick Cheney at first said that "we've not been eager to give the guy any extra television time." And spokesman Ari Fleischer mysteriously said, "There are just issues involving protecting people who were there, who have knowledge about how it was obtained."
But by that time, summaries of the tape had been widely leaked, and also word that the tape had been found by American investigators in a house in Jalalabad. Any compromising of sources and methods (payment to the man who had made the amateur videotape?) had presumably already happened. But officials are reluctant to abandon the "sources and methods" routine.
Similarly, the FBI has a problem with the unexplained alerts it has issued three times now to a nervous public. The alerts are based, it says, on "credible evidence" that it cannot discuss because of "sources and methods." One can surmise the nature of some of the "credible evidence." Someone is overheard talking about a prospective attack whose credibility comes from having been overheard in advance of a previous attack.
Is it not likely that terrorists are aware of being monitored and can match their conversations to the subsequent alerts? Has the FBI considered the possibility that some of the ominous conversations involve game-playing deliberately intended to engender fear?
Protection of sources and methods remains a legitimate intelligence concern, and one could wish it were always respected by those responsible for it. In 1983, for example, President Reagan was anxious to prove that the Soviets had deliberately shot down a Korean airliner that had strayed into their territory - which they denied. The president ordered that the tape of a Soviet fighter pilot closing in for the kill on the passenger plane be played for the United Nations Security Council.
It was a spectacular piece of theater, but it was disclosed despite the strenuous advice of the intelligence community. The tape came from a super-secret electronic monitoring facility on a northern Japanese island that was compromised by the president's disclosure of secret sources and methods.
Daniel Schorr is a senior news analyst at NPR.