We are hearing a new concept these days in discussions about Iran — the zone of immunity. The idea, often explained by Ehud Barak, Israel’s defense minister, is that soon Iran will have enough nuclear capability that Israel would not be able to inflict a crippling blow to its program.

In fact, while the specifics are fresh, this is not a new strategic concept at all. Nations have often believed that they face a closing window to act, and almost always such thinking has led to disaster. The most famous example, of course, was Germany’s decision to start what became World War I. The German General Staff believed that Russia — its archenemy — was rearming on a scale that would soon nullify Germany’s superior military strength. The Germans believed that within two years — by 1916 — Russia would have a significant, and perhaps unbeatable, strategic ­advantage.

As a result, when turmoil began in the Balkans in June 1914, Germany decided to act while it had the advantage. To stop Russia from entering a “zone of immunity,” Germany invaded France (Russia’s main ally) and Belgium, which forced British entry into the war, thus setting in motion a two-front European war that lasted four years and resulted in more than 37 million casualties.

Now, I am not suggesting that an Israeli attack on Iran would have anything close to these consequences. But I am suggesting that it is profoundly shortsighted to base a major decision — to go to war — on narrow technical considerations like windows of vulnerability. Many in Washington in March 2003 insisted that we could not wait for nuclear inspectors to keep at their work in Iraq because we faced a closing window — the weather was going to get too hot by June and July to send in U.S. forces. As a result, we rushed into a badly planned military invasion and occupation in which soldiers had to endure combat in Iraq for nine long and very hot years.

Israeli officials explain that we Americans cannot understand their fears, that Iran is an existential threat to them. But in fact we can understand because we have gone through a very similar experience ourselves. After World War II, as the Soviet Union approached a nuclear capability, the United States was seized by a panic that lasted for years. Everything that Israel says about Iran now, we said about the Soviet Union. We saw it as a radical, revolutionary regime, opposed to every value we held dear, determined to overthrow the governments of the Western world in order to establish global communism. We saw Moscow as irrational, aggressive and utterly unconcerned with human life. After all, Joseph Stalin had just sacrificed a mind-boggling 26 million Soviet lives in his country’s struggle against Nazi Germany.

Just as Israel is openly considering preemptive strikes against Iran, many in the West urged such strikes against Moscow in the late 1940s. The calls came not just from hawks but even from lifelong pacifists such as the public intellectual Bertrand Russell.

To get a sense of the mood of the times, consider this entry from the Nov. 29, 1948, diary of Harold Nicolson, one of the coolest and most sober British diplomats of his generation: “[I]t is probably true that Russia is preparing for the final battle for world mastery and that once she has enough bombs she will destroy Western Europe, occupy Asia, and have a final death struggle with America. If that happens and we are wiped out over here, the survivors in New Zealand may say that we were mad not to have prevented this. . . . There is a chance that the danger may pass and peace can be secured with peace. I admit it is a frail chance, not one in ninety.”

In a speech at the Boston Navy Yard in August 1950, Navy Secretary Francis Matthews argued that, in being “an initiator of a war of aggression,” the United States “would become the first aggressors for peace.”

In the end, however, the global revolutionaries in Moscow, the mad autocrats in Pyongyang and the terrorist-supporting military in Pakistan have all been deterred by mutual fears of destruction. While the Iranian regime is often called crazy, it has done much less to merit the term than did a regime such as Mao’s China. Over the past decade, there have been thousands of suicide bombings by Saudis, Egyptians, Lebanese, Palestinians and Pakistanis, but not been a single suicide attack by an Iranian. Is the Iranian regime — even if it got one crude device in a few years — likely to launch the first?

“Israel is finally confronting the sort of choices the United States and Great Britain confronted more than six decades ago,” says Gideon Rose, the editor of Foreign Affairs. “Hopefully it, too, will come to recognize that absolute security is impossible to achieve in the nuclear age, and that if its enemies’ nuclear programs cannot be delayed or disrupted, deterrence is less disastrous than preventive war.”comments@fareedzakaria.com (© 2010 The Washington Post Company 02/16/12)