Sen. John McCain has repeatedly characterized the threat of "radical Islamic extremism" as "the absolute gravest threat ... that we're in against." Before we simply accept this, we need to examine the nature of the terrorist threat facing our country. If we do so, we will see how we have allowed the specter of that threat to distort our lives and take our treasure.

The "Global War on Terror" has conjured the image of terrorists behind every bush, the bushes themselves burning, and an angry god inciting its faithful to religious war. We have been called to arms, built fences, and compromised our laws and the practices that define us as a nation. The administration has focused on pursuing terrorists and countering an imminent and terrifying threat. Thousands of Americans have died as a result, as have tens of thousands of foreigners.

The inclination to trust our leaders when they warn of danger is compelling, particularly when the specters of mushroom clouds and jihadists haunt every debate. McCain, accepting this view of the threats, pledges to continue the Bush administration's policy of few distinctions but ruthless actions.

I spent 23 years in the CIA. I drafted or was involved in many of the government's most senior assessments of the threats facing our country. I have devoted years to understanding and combating the jihadist threat.

We rightly honor as heroes those who serve our nation and offer their lives to protect ours. We all "support the troops." Yet the first step for any commander is to understand the enemy. The next commander in chief should base his counterterrorism policies on the following realities:

We do not face a global jihadist "movement" but a series of disparate ethnic and religious conflicts involving Muslim populations, each of which remains fundamentally regional in nature and almost all of which long predate the existence of al-Qaida.

Osama bin Laden and his disciples are small men and secondary threats whose shadows are made large by our fears. Al-Qaida is the only global jihadist organization and is the only Islamic terrorist organization that targets the U.S. homeland. Al-Qaida remains capable of striking here and is plotting from its redoubt in Waziristan, Pakistan. The organization, however, has only a handful of individuals capable of planning, organizing and leading a terrorist operation. Al-Qaida threatens to use chemical, biological, radiological or nuclear weapons, but its capabilities are far inferior to its desires. Even the "loose nuke" threat, whose consequences would be horrific, has a very low probability. For the medium term, any attack is overwhelmingly likely to consist of creative uses of conventional explosives.

No other Islamic-based terrorist organization, from Mindanao to the Bekaa Valley to the Sahel, targets the U.S. homeland; is part of a "global jihadist movement"; or has more than passing contact with al-Qaida. These groups do and will, however, identify themselves with global jihadist rhetoric and may bandy the bogey-phrase of "al-Qaida." They are motivated by hostility toward the West and fear of the irresistible changes that education, trade, and economic and social development are causing in their cultures. These regional terrorist organizations may target U.S. interests or persons in the groups' historic areas of interest and operations. None of these groups is likely to succeed in seizing power or in destabilizing the societies they attack, though they may succeed in killing numerous people through sporadic attacks such as the Madrid train bombings.

There are and will continue to be small numbers of Muslims in certain Western countries — in the dozens, perhaps — who seek to commit terrorist acts, along the lines of the British citizens behind the 2005 London bus bombings. Some may have irregular contact with al-Qaida central in Waziristan; more will act as free agents for their imagined cause. They represent an Islamic-tinged version of the anarchists of the late 19th century: dupes of "true belief," the flotsam of revolutionary cultural change and destruction in Islam, and of personal anomie. We need to catch and neutralize these people. But they do not represent a global movement or a global threat.

The threat from Islamic terrorism is no larger now than it was before Sept. 11, 2001. Islamic societies the world over are in turmoil and will continue for years to produce small numbers of dedicated killers, whom we must stop. U.S. and allied intelligence do a good job at that; these efforts, however, will never succeed in neutralizing every terrorist, everywhere.

Why are these views so starkly at odds with what the Bush administration has said since the beginning of the "Global War on Terror"? This administration has heard what it has wished to hear, pressured the intelligence community to verify preconceptions, undermined or sidetracked opposing voices, and both instituted and been victim of procedures that guaranteed that the slightest terrorist threat reporting would receive disproportionate weight — thereby comforting the administration's preconceptions and policy inclinations.

We must not delude ourselves about the nature of the terrorist threat to our country. We must not take fright at the specter our leaders have exaggerated. In fact, we must see jihadists for the small, lethal, disjointed and miserable opponents that they are.

Glenn L. Carle was a member of the CIA's Clandestine Service for 23 years and retired in March 2007 as deputy national intelligence officer for transnational threats. He wrote this commentary for The Washington Post.