The 20th century was replete with superfluous wars, so much so that today many people in the West have developed a well intentioned and deeply ingrained knee jerk reaction against all wars. In the age of "post" everything, awareness of history and recognition of the crucial role of context for understanding our world have been largely eschewed for a fragmented and disjointed approach that leads to distortion, and confusion, and has greatly impaired our ability to make meaningful comparisons. Coupled with this "post" mentality, the strong strain of indiscriminate pacifism has largely blinded people to the fact that, as much as we may wish there were none, some wars are justified. In the last century, the archetypal just war was that fought against Nazi Germany and its partners. The Nazis, with their hate-imbued ideology, their perpetration of colossal atrocities, their overall savagery and brutality, and their plans to take over the world and remake it in their own image, have emerged as the measure for radical evil. Before the free world recognized that such a radical evil had to be fought with no holds barred, it tried to placate the beast, rationalizing some of its demands and trying to "understand" some of its early heinous acts. At the heart of this radical evil lay an anti-Semitic and racial ideology that targeted all Jews for death. It also engendered the selective mass murder, enslavement, and rapacious plunder and exploitation of countless others. The enlightened world paid a large price for its slow conclusion that it must fight tooth and nail against the Nazis. When it finally united and threw in its entire weight, it faced an uphill battle. The loss of human life and possession were immense before the Allies were finally able to overcome their foe. By the time the Nazis were vanquished, the Holocaust had claimed six million Jews, millions of others died in related direct and implicit acts of murder, and millions of soldiers and civilians perished in the war. NUMEROUS MEDIA reports about the war that were colored by a visceral anti-Israel bias and the UN resolution concerning the fighting in Lebanon unmistakably testify that the nations of the world have yet to unite behind an understanding that once again there is a radical evil in the world. It is a two-headed hydra - the Iranian regime under Mahmoud Ahmadinejad (with Hizbullah its unmistakable proxy), and the diverse terrorist groups associated with al- Qaida, under Osama Bin Laden - rooted in twisted versions of Islam. It is not by accident that the hydra, in both of its manifestations, blames Israel and the Jews for the ills of the world, and has targeted Israel for destruction. Ahmadinejad, who has been deemed by the world's more perceptive politicians the new Hitler, has publicly and unequivocally threatened Israel on several occasions. As Hitler demonstrated 70 years ago, threats made by such leaders must be taken seriously. The current menace is not identical to Nazism: first and foremost, it is rooted in a different set of values. But it does have similarities. Like the Nazis before them, the Iranian state officially sponsors anti-Semitism, although they have added the newer seasoning of Holocaust Denial. The most current expression of their ardent Jew-hatred is the newly opened exhibit in Teheran, of cartoons mocking the Holocaust. Since the end of the Second World War, other states have sponsored anti-Semitism, officially and obliquely, but none before Iran have ever made explicit declarations about their intentions to destroy the Jews, nor has any other state invested such a great effort to gain the means to turn their threats into actions. In addition to targeting the Jews for genocide, Islamic fundamentalism stands firmly against the values held dear by the free world and, like the Nazis, the hydra evinces no normative moral considerations whatsoever. Hizbullah's cynical use of civilian populations as human shields and its intentional targeting of civilian targets in Israel, including the lives of brother Muslims living where it sent its deadly rocket fire, all too clearly illustrate its total dearth of time-honored moral concerns. That the rest of the world has allowed Hizbullah to survive does not bode well for the future. The very fact that it still exists will strengthen its resolve and the resolve of those who stand behind it. Terrorist cells, some linked to Iran and others linked to Bin-Laden, will undoubtedly continue to try to carry out unmitigated acts of terror, like the plan to explode at least 10 airplanes headed from London to the United States. Hizbullah's godfather Ahmadinejad retains his unrepentant desire to attain nuclear capabilities and continues his unrelenting march toward this goal. Alas, the world has begun its response to radical evil slowly and weakly, just as it did in the time of the Nazis. Will it eventually come around and take decisive and appropriate action, despite the unavoidable heartbreak of war, or will it do too little, too late? The key lies in recognizing and understanding the extent of the threat, and acting with courage, conviction and unswerving determination until that threat has been extinguished. The writer is the director of the Yad Vashem Libraries, author of Approaching the Holocaust, Texts and Contexts, and co-editor of The Holocaust: Frequently Asked Questions.