I've written at length many times before about how many supposed foreign affairs "experts" exhibit complete historical ignorance and astonishingly poor understanding of basic international relations. Dan Senor's analysis of the Iranian threat in the Wall Street Journal is a case in point.

"Iran is not the Soviet Union," he writes, "and the post-9/11 struggle is not the Cold War. The deterrence camp is willing to stand by as Iran develops nuclear weapons, presumably on the model that Iran will eventually collapse as the Soviet Union did. But the Argentinean case [Iran's terrorist bombings of Jewish and Israeli targets in Buenos Aires in 1992 and 1994] demonstrates what Tehran was willing and able to do when it had no nuclear umbrella."

Senor seems to be under the impression that the Soviet Union never sponsored terrorism against its Western adversaries, the way Iran has. In fact, the Soviets provided ample support, in the form of arms, training and sanctuary, to various international terrorist groups during the 1970s and 1980s. It was also, lest we forget, willing to supply nuclear weapons (under its own control, we assume) to its ally Cuba. In its ruthless ambition for world domination, Communist ideology was second to none--including Islamism.

The lessons of the Cold War, properly understood, actually apply very well to the Iranian situation. The Cold War demonstrated that nuclear deterrence works--in the absence of proliferation. The Cuban missile crisis and centralization-obsessed Soviet dogma ensured that Soviet-made nuclear weapons would not be used except on the orders of the Soviet Politburo--and the American nuclear deterrent ensured that the Soviet Politburo could never afford such a risk. The Iranian government is almost certain to be similarly deterred from launching a direct nuclear attack, should it acquire the means to do so. Whether it will be as careful as the Soviet Union about husbanding its nuclear capacity is a more difficult and worrisome question.

But as the Cold War also taught us, nuclear and non-nuclear conflict are eminently separable. Nuclear deterrents, whether American, Soviet, Israeli or Iranian, are effective primarily against existential threats, of the kind that nobody is likely to mount against Iran in any event. But they do not prevent an adversary such as the Soviet Union or Iran from engaging in all manner of attritive combat, from proxy wars to terrorism, and even direct limited-theater military attack.

What the Cold War taught us about such conflicts is that they can and should be answered in kind. During the late 1970s, when the US was in full retreat, Soviet proxies, including aggressive allied nations, insurgent groups and terrorist organizations, attacked the Western world and its allies virtually unopposed. The Reagan doctrine--that Communist victories can be not only resisted, but actually reversed--changed all that, forcing the Soviets to expend their resources on defense as well as offense (in Nicaragua, Afghanistan, and many other places), and thus reversing all the political momentum the Soviets had built up following Vietnam. Whether or not it was the primary reason for the collapse of the Soviet Union, as I've speculated, it was most likely an expediting factor.

The Iranian nuclear program can plausibly be compared with the Cuban missile crisis, in that an American enemy threatens to cross an important nuclear proliferation threshold. But the Cold War didn't end with the Cuban missile crisis, nor will the conflict between the US and Iranian-led radical Islamism end with the final success or failure of Iran's nuclear ambitions. If the Cold War is any guide, the outcome of that conflict will likely depend more on what the US does to confront and counter Islamists' global exercise of power, than on how it manages the nuclear stalemate that will ultimately exist regardless of whether Iran manages to build atomic bombs. America's lethargic response so far to aggressive Iranian operations in Iraq suggests that the current administration has yet to learn this lesson.