The problem with showing our Iraq evidence at the U.N.

As the world waits for Feb. 5, the date when Secretary of State Colin Powell plans to brief the U.N. Security Council and finally unveil the top-secret intelligence materials that (so we're promised) prove Iraq is hiding weapons of mass destruction, two points are worth making.

First, however compelling Powell's show-and-tell might be, it is extremely unlikely that his case will be as cut-and-dried as Adlai Stevenson's display of U-2 spy plane photographs in October 1962 (everybody's favorite parallel), which proved beyond all doubt that the Soviets were installing nuclear missiles in Cuba.

Second, in part for that reason, U.S. intelligence officers, who are putting up fierce internal resistance to declassifying the Iraqi evidence, probably have good reasons for their dissent.

Their big concern is that the United States will blow a lot of highly sensitive intelligence data—the sort of sources and methods that are rarely even discussed, never deliberately revealed—and the cache still won't be persuasive enough, especially not to the layman, to justify war.

Nobody on the outside knows exactly what sort of data dump Powell is assembling. But one can make some guesses and extrapolate reasons why the spy agencies might be nervous.

Images from spy-satellite photos are the most obvious but least problematic category. Anyone can download such imagery from commercial variants of these satellites. The principles of what the cameras do, and how to evade them, are fairly well-understood. Even here, though, there are some issues. The publicly released versions of these photos have a resolution of about 1 meter (i.e., they can distinguish objects that are 1 meter wide). However, these are "scrubbed" versions. The real, unvarnished photos are believed to have much sharper resolution, around one-tenth of a meter. If some of Powell's case requires revealing the sharper images, world leaders (not just Saddam) will then know just how good our eyes-in-the-sky are—and how much better they need to hide whatever they don't want us to see.

More serious are intercepts from telephone conversations, which Bush suggested in his State of the Union message that we possess. Information from them could be revealing enough to prompt Iraq's leaders to shut down certain phone lines—and possibly kill people whose lines were tapped.

There is a precedent here. In the late 1970s, an anti-detente CIA analyst leaked to the columnist Jack Anderson some transcripts of phone conversations from Leonid Brezhnev's car, suggesting (or so the analyst thought) that Soviet delegates to the SALT II arms control talks were manipulating the treaty to allow them to keep building certain types of ICBMs that the American negotiators thought would be banned. After Anderson published the leak, the tap on the car disappeared—as did the Soviet mechanic whom the CIA had hired to install it.

It is also possible that our spy agencies have learned some information by tapping into a command-level fiber-optics cable system that the Iraqis had thought was secure—and that, after Wednesday, they would know is not.

I should emphasize: I do not know—nor has anyone suggested—that such a system exists or that we have figured out how to intercept its transmissions. But here, too, there is a telling precedent. In the late Cold War, when Soviet submarines returned to port, they downloaded their databanks into a cable. These databanks told everything about where the sub had gone, what it had done, how its fuel systems worked—everything. In the 1980s, American SEALs navigated minisubs into Soviet harbors and tapped into these cables. Everything they transmitted, we intercepted. An NSA analyst named Ronald Pelton revealed this operation to the Soviets. As a result, the Soviets shut down the cables and switched to microwave transmission. (Pelton was arrested and convicted for his espionage.)