‘‘And mark my words, he will develop weapons of mass destruction. He will deploy them, and he will use them’’ -- President Clinton, Dec. 16, 1998

…the botched terror assessment [of Britain's intelligence agencies] raises a question for us, too: Which kind of intelligence failure is better — the kind that badly understates a threat, such as the one in London [three weeks before the London bombings of July 7, Britain’s Joint Terrorist Analysis Center advised policymakers that "at present there is not a group with both the current intent and the capability to attack the UK"], or the kind that overstates a threat, such as the insistent warnings before the invasion of Iraq that Saddam Hussein was armed with weapons of mass destruction?

Of course no intelligence failure is desirable. But even in the best intelligence services, they are sometimes inevitable. Foresight will never be as sharp as hindsight. Only after the fact -- after the Underground blows up, after 9/11, after the stockpiles of biological and chemical weapons are nowhere to be found -- is it clear what the picture looks like once the ‘‘dots’’ are ‘‘connected.’’ Before the fact, it isn’t always clear that there are even any dots to search for, let alone what shape they might take or how reliable they might be.

So what kind of culture do we want intelligence agencies to foster among their operatives and analysts: one that tends to be overly focused on possible threats, or one that is more likely to downplay them? In general, would we rather take action to eliminate a danger that turns out to have been overstated -- or take no action, and then be stunned when the enemy strikes?

Surely the question answers itself. When the enemy is an international terrorist organization or a violent and dictatorial regime, preemption must trump reaction. Ousting the most brutal and homicidal tyrant in the Arab world, even if we then discover that he didn’t pose the WMD threat we had envisioned, beats watching Osama bin Laden’s acolytes steer jetliners into the World Trade Center. Bombing the Iraqi nuclear plant at Osirak, as Israel did in 1981, beats waiting until Iraq launches its first nuclear strike.

…most Americans understand that intelligence failures are not the same thing as lies. And the intelligence failures about Saddam Hussein['s] WMD capability did not begin under the incumbent President Bush. Back when his father was president, before the first Iraq war, the CIA badly underestimated the extent of Saddam’s quest for chemical, biological, and nuclear weapons.

Fortunately, Saddam was stupid enough to invade Kuwait. That triggered the Gulf War, in the course of which the world discovered just how deadly a WMD menace the Iraqi butcher had become.

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