RIDAY HARBOR, Wash. ・September 11, 2001, like December 7, 1941, is surely a date that will live in infamy. But despite superficial similarities, Tuesday's events were no kind of Pearl Harbor. Harrowing as it is to contemplate, they may ultimately prove even more challenging, perhaps even more insidiously consequential, than the notorious sneak attack that plunged the United States into World War II. To think otherwise is not merely misleading, but dangerous.

To be sure, both events inflicted unspeakable carnage and unleashed torrents of fear and outrage, as well as pledges of national solidarity and cries for vengeance without mercy. But there the resemblance ends. Among the more chilling differences, the Manhattan and Pentagon death tolls will almost certainly dwarf the total of 2,403 Americans who perished at Pearl Harbor.

What is more, the American naval and air bases in Hawaii on that Sunday morning in 1941 came under attack from a conventional naval force (albeit one employing the wholly new tactic of seaborne air power) deployed by a state whose identity and aspirations were no mystery. The Japanese Navy struck at those military facilities to achieve highly traditional military and diplomatic objectives: neutralization of America's Pacific fleet and perhaps a negotiated political settlement with an isolationist United States that appeared to have little stomach for war, in order to secure Japanese access to Indonesian oil and, ultimately, a free hand to pursue further aggression in Asia. It was a desperate and ultimately doomed gamble, but not an insane one, and it was undertaken for reasons all too familiar in the annals of warfare and politics.

Even more to the point is the American reaction to Pearl Harbor. The United States responded in just the way the Japanese most feared: it reflexively dismissed the notion of negotiation, insisted on unconditional surrender and proceeded to mobilize with astounding speed, energy and ingenuity. It fought the kind of war for which it was ideally suited, drawing on vast pools of manpower, money and machinery to achieve the production miracle that culminated in the nuclear destruction of Hiroshima and Nagasaki in August 1945. As the more astute Japanese leaders had anticipated, an eventual American victory was a foregone conclusion if the United States managed to shake off the initial blow and fully energize its behemoth economy for martial purposes.

The contrast with the current scenario is vivid. Now we have attacks on civilian and symbolic targets by highly unconventional forces under the command of still unidentified parties with unknown ambitions. Amid the past week's din of destruction, nothing was more eerie and unsettling than the silence of our attackers and their studied refusal to specify their demands. Whoever our adversaries are, their objectives are not measured in terms of geography, trade or any of the usual markers of political rivalry. They seek not simply to destroy but to demoralize, not to seize territory but to sow chaos, not to conquer so much as to cripple and corrupt. They are targeting not only lives and property but our most fundamental values, including our commitments to personal liberty and to the institutions of an open society.

These are not the kind of provocations that can be countered simply by mustering the nation's prodigious human, financial and industrial brawn, the winning strategy in World War II. We are instead facing the distressing spectacle of history's richest and most powerful nation rendered the victim of an elusive foe impervious to the military might we have spent decades building. Perhaps because of the lingering mystique of the Pearl Harbor memory, as Ashton B. Carter and former Defense Secretary William J. Perry argued in their trenchant 1999 book "Preventive Defense," we have persisted in building a military force designed to fight the last war while neglecting to cope with the altogether new threat of catastrophic terrorism, a threat now made spectacularly real.

It is often said that Pearl Harbor forever ended American isolationism. And it is certainly true that World War II transformed the United States from a marginal to a dominant player in the international arena, and from a Depression-stricken land into the model of modern affluence ・the very developments that now excite the vicious anti-Americanism that appears to have inspired last week's atrocities.

But a blow to a military outpost at Pearl Harbor, far removed from the American heartland, is scarcely comparable to strikes against the nation's largest city and its capital. And despite decades of preparation for nuclear war, the fact is that the attack on September 11, 2001, was perpetrated not with the deadly weapons of our old adversaries, but with commandeered commercial airliners ・the proud fruits of a technologically advanced and prosperous society. That choice of weapons, with all their symbolic resonance, underscores the newness of this threat. Against it our conventional arsenal is all but useless, and so are conventional definitions of victory. In World War II we utterly destroyed our adversaries' fighting capacity and forced them to capitulate on terms we dictated. But what weapons should we take up now? Against whom? To what ultimate purpose?

Most sobering of all is the prospect that in our rage and anguish we will compromise our principles of freedom and openness. The battle now joined will be waged on our soil, with all the attendant risk of collateral damage to the delicate fabric of democracy, as rising threats against Arab-Americans and Muslims, and cries for restrictions on civil liberties, already portend.

President Bush has rightly described this week's attacks as assaults on the "foundation of America," although his administration, perhaps for understandable reasons, has thus far seemed more preoccupied with undertaking reprisals, World War II-style, than with shoring up that threatened foundation. Yet as surely as World War II restored confidence and pride to a people worn down by the Great Depression, the attacks of September 11 have the potential to diminish the liberty and individual rights that have been among this society's healthiest attributes.

We must retaliate for the crimes of September 11. But we must also reconfigure our defenses to meet the security challenges of this new era. And we must attend with no less passion and care to preserving those values that have made our society distinctive and for which the World War II generation ・and other generations before it ・fought. More is at stake here than a misappropriated historical analogy. The very character of our society is at risk. Comforting incantations about our resolve and might are no longer sufficient, nor are memories of a time when sheer military and economic muscle could bring our enemies to their knees. As Abraham Lincoln said in another hour of national peril, "as our case is new, so we must think anew, and act anew. We must disenthrall ourselves, and then we shall save our country."

David M. Kennedy, professor of history at Stanford University, won a Pulitzer Prize in 2000 for "Freedom From Fear: The American People in Depression and War, 1929-1945."