As Zarqawi described in his letter and in subsequent broadcasts, his strategy in Iraq is to strike at the Shia -- and thereby provoke a civil war. "A nation of heretics," the Shia "are the key element of change," he wrote. "If we manage to draw them onto the terrain of partisan war, it will be possible to tear the Sunnis away from their heedlessness, for they will feel the weight of the imminence of danger." Again a strategy of provocation -- which plays on an underlying reality: that Iraq sits on the critical sectarian fault line of the Middle East and that a conflict there gains powerful momentum from the involvement of neighboring states, with Iran strongly supporting the Shia and with Saudi Arabia, Kuwait, Jordan and Syria strongly sympathetic to the Sunnis. More and more, you can discern this outline in the chaos of the current war, with the Iranian-trained militias of the Shia Islamist parties that now control the Iraqi government battling Sunni Islamists, both Iraqi and foreign-born, and former Baathists.

In the midst of it all, increasingly irrelevant, are the Americans, who have the fanciest weapons but have never had sufficient troops, or political will, to assert effective control over the country. If political authority comes from achieving a monopoly on legitimate violence, then the Americans, from those early days when they sat in their tanks and watched over the wholesale looting of public institutions, never did achieve political authority in Iraq. They fussed over liberalizing the economy and writing constitutions and achieving democracy in the Middle East when in fact there was really only one question in Iraq, emerging again and again in each successive political struggle, most recently in the disastrously managed writing of the constitution: how to shape a new political dispensation in which the age-old majority Shia can take control from the minority Sunni and do it in a way that minimized violence and insecurity -- do it in a way, that is, that the Sunnis would be willing to accept, however reluctantly, without resorting to armed resistance. This might have been accomplished with hundreds of thousands of troops, iron control and a clear sense of purpose. The Americans had none of these. Instead they relied first on a policy of faith and then on one of improvisation, driven in part by the advice of Iraqi exile "friends" who used the Americans for their own purposes. Some of the most strikingly ideological decisions, like abruptly firing and humiliating the entire Iraqi Army and purging from their jobs many hundreds of thousands of Baath Party members, seemed designed to alienate and antagonize a Sunni population already terrified of its security in the new Iraq. "You Americans," one Sunni businessman said to me in Baghdad last February, shaking his head in wonder, "you have created your own enemies here."

The United States never used what authority it had to do more than pretend to control the gathering chaos, never managed to look clearly at the country and confront Iraq's underlying political dysfunction, of which the tyranny of Saddam Hussein was the product, not the cause. "The illusionists," Ambassador John Negroponte's people called their predecessors, the officials of the Coalition Provisional Authority under L. Paul Bremer III. Now, day by day, the illusion is slipping away, and with it what authority the Americans had in Iraq. What is coming to take its place looks increasingly like a failed state.

VI. It is an oft-heard witticism in Washington that the Iraq war is over and that the Iranians won. And yet the irony seems misplaced. A truly democratic Iraq was always likely to be an Iraq led not only by Shia, who are the majority of Iraqis, but by those Shia parties that are the largest and best organized -- the Supreme Council for the Islamic Revolution in Iraq and the Dawa Islamic Party -- which happen to be those blessed by the religious authorities and nurtured in Iran. Nor would it be a surprise if a democratic Saudi Arabia turned out to be a fundamentalist Saudi Arabia and one much less friendly to the United States. Osama bin Laden knows this, and so do American officials. This is why the United States is "friendly" with "apostate regimes." Democratic outcomes do not always ensure friendly governments. Often the contrary is true. On this simple fact depends much of the history of American policy not only in the Middle East but also in Latin America and other parts of the world throughout the cold war. Bush administration officials, for all their ideological fervor, did the country no favor by ignoring it.

In launching his new cold war, George W. Bush chose a peculiarly ideological version of cold-war history. He opted not for containment, the cautious, status quo grand strategy usually attributed to the late George F. Kennan, but for rollback. Containment, by which the United States determinedly resisted Soviet attempts to expand its influence, would have meant a patient, methodical search for terrorists, discriminating between those groups that threaten the United States and those that do not, pursuing the former with determined, practical policies that would have drawn much from the military and law-enforcement cooperation of our allies and that would have included an effective program of nonproliferation to keep weapons of mass destruction out of terrorist hands. Rollback, on the other hand, meant something quite different; those advocating it during the 1950's considered containment immoral, for it recognized the status quo: Communist hegemony in Eastern Europe and parts of Asia. They wanted instead to destroy Communism entirely by "rolling back" Communists from territory they had gained, as Gen. Douglas MacArthur did briefly and, it turned out, catastrophically, in North Korea, and as President Eisenhower refused to do when he declined to support the Hungarian revolutionaries against the Soviet invasion in 1956.

The original advocates of rollback lost that struggle. In this new cold war, the rollback advocates triumphed and adopted as the heart of their policy a high-stakes, metaphysical gamble to "democratize the Middle East" and thus put an end, once and for all, to terrorism. They relied on a "domino theory" in which the successful implantation of democracy in Iraq would lead to a "democratic revolution" across the region. The ambition of this idea is breathtaking; it depends on a conception of American power as virtually limitless and on an entirely fanciful vision of Iraqi politics, a kind of dogged political wish-fulfillment that no sober analysis could penetrate. Replacing any real willingness to consider whether a clear course existed between here and there, between an invasion and occupation of Iraq and a democratic Middle East, was, at bottom, the simple conviction that since the United States enjoyed a "preponderance of power" unseen in the world since the Roman Empire, and since its cause of democratic revolution was so incontrovertibly just, defeat was inconceivable. One detects here an echo of Vietnam: the inability to imagine that the all-powerful United States might lose.

American power, however, is not limitless. Armies can destroy and occupy, but it takes much more to build a lasting order, especially on the shifting sands of a violent political struggle: another Vietnam echo. Learning the lesson this time around may prove more costly, for dominoes can fall both ways. "Political engineering on this scale could easily go awry," Stephen D. Biddle, a U.S. Army War College analyst, wrote this past April in a shrewd analysis. "If a democratic Iraq can catalyze reform elsewhere, so a failed Iraq could presumably export chaos to its neighbors. A regionwide Lebanon might well prove beyond our capacity to police, regardless of effort expended. And if so, then we will have replaced a region of police states with a region of warlords and chronic instability. This could easily prove to be an easier operating environment for terrorism than the police states it replaces."