In any war, good intelligence is critical. It's difficult to defeat an enemy if you don't know what the enemy is planning to do.

Yet, more than five years into the war against terrorism, we still don't even know how many enemy fighters we're up against.

The recent leak of a portion of the National Intelligence Estimate led to newspaper headlines proclaiming that the war on terror is "creating more terrorists" than it's getting rid of. Then, when more of the estimate was declassified, many were left wondering, "How would we know that, and what does it mean?"

The headlines make it sound as if there are plenty of authoritative studies indicating that there are more terrorists now than there were five years ago. The reality is, we could never know. Did we have accurate databases of how many terrorists there were in the world on Sept. 11? Do we know how many terrorists there are now?

We know that the number of terrorist acts is up, but even here the data are unclear. The way the U.S. government counts attacks has changed, so it's difficult to compare recent data with past years. And the number is wildly skewed by counting every terrorist attack in Iraq as an incident of international terrorism, when many of them are about domestic sectarian conflict.

Nobody seems to definitively know how many terrorists there are. In a now-famous February 2003 memo, Defense Secretary Donald Rumsfeld asked, "Are we capturing, killing or deterring and dissuading more terrorists every day than the madrassas and the radical clerics are recruiting, training and deploying against us?" That was no mere rhetorical question. He didn't know the answer.

If there are more terrorists, is that because of the American effort to fight transnational terrorism? After all, we know that in the half dozen years leading up to Sept. 11 the United States made only very modest efforts to combat transnational terrorism, yet the threat grew.

During that time, Osama bin Laden built one of the most sophisticated and expansive networks in history, a network that has been severely disabled.

And, if there are more terrorists in the world, is that a sign of failure? During World War II, German war production increased during the course of the war, almost to the bitter end, but Germany lost anyway. In fact, the first American act of World War II, declaring war on Japan, doubled the number of enemies we faced because Germany almost immediately declared war on the U.S. Was declaring war on Japan a bad decision? Counting numbers out of context may not tell you much.

The number of terrorists may be less important than who they are and where they are.

For example, if the process of tracking down and getting one senior al-Qaida official spawned 30 al-Qaida wannabes who were far less capable than al-Qaida, is that really a bad trade-off?

And since terrorists are a tiny percentage of virtually any group (except other terrorists), they remain a miniscule part of the population. Even if the number of terrorists in the world were to double, the total number would remain small.

Counting numbers makes even less sense when we consider how many (or how few) terrorists it takes to kill or traumatize a great many people.

It took only 19 hijackers to terrorize New York and Washington. One terrorist can be a real problem.

On the other hand, by some estimates upward of 40,000 people trained at the terrorist camps in Afghanistan before Sept. 11. Yet we have no evidence indicating that many of them went on to become serious killers.

Declaring that the war on terror is "creating more terrorists" than it's getting rid of is more of a bumper-sticker slogan than a serious attempt to gauge our progress in this long war. Americans deserve better than empty rhetoric.

James Jay Carafano is senior research fellow for national security and homeland security at The Heritage Foundation (www.heritage.org), and author of the new book "G.I. Ingenuity."