In response to the test of foreign affairs that then Senator Biden foresaw during last year's presidential campaign, President Obama, brilliantly wielding the powers of his office, has managed to fail not just once but twice. In a single week in September, he buckled in the face of Russian pressure and he took a giant wooden nickel from Iran.

With both a collapsing economy and natural gas reserves sufficient to produce 270 years of electricity, the surplus of which it exports, Iran does not need nuclear electrical generation at a cost many times that of its gas-fired plants. It does, however, have every reason according to its own lights to seek nuclear weapons—to deter American intervention; to insure against a resurgent Iraq; to provide some offset to nearby nuclear powers Pakistan, Russia, and Israel; to move toward hegemony in the Persian Gulf and address the embarrassment of a more militarily capable Saudi Arabia; to rid the Islamic world of Western domination; to neutralize Israel's nuclear capacity while simultaneously creating the opportunity to destroy it with one shot; and, pertinent to the week's events, by nuclear intimidation to turn Europe entirely against American interests in the Middle East.

Some security analysts may comfort themselves with the illusion that soon-to-be nuclear Iran is a rational actor, but no country gripped so intensely by a cult of martyrdom and death that to clear minefields it marched its own children across them can be deemed rational. Even the United States, twice employing nuclear weapons in World War II, seriously contemplated doing so again in Korea and then in Vietnam.

The West may be too pusillanimous to extirpate Iran's nuclear potential directly, but are we so far gone as to foreswear a passive defense? The president would have you think not, but how is that? We will cease developing the ability to intercept, within five years, the Intercontinental Ballistic Missiles (ICBMs) that in five years Iran is likely to possess, in favor of a sea-based approach suitable only to Iranian missiles that cannot from Iranian soil threaten Rome, Paris, London, or Berlin. Although it may be possible to modify Block II Standard Missiles with Advanced Technology Kill Vehicles that could disable any Iranian missiles in their boost phase, this would require the Aegis destroyers carrying them to loiter in the confined and shallow waters of the Persian Gulf, where anti-missile operations would be subject to Iranian interference and attack.

Interceptors that would effectively cover Western Europe are too big for the vertical launch cells of the Aegis ships, or even their hulls. Thus, in light of the basing difficulties that frustrate a boost-phase kill, to protect Europe and the United States the president proposes to deploy land-based missiles in Europe at some future date. If he is willing to do this, why not go ahead with the current plans? The answer is that, even if he says so, he will not deploy land-based missiles in Europe in place of the land-based missiles in Europe that he has cancelled because they are land-based in Europe.

What we have here is an inadvertent homage to Lewis Carroll: We are going to cancel a defense that takes five years to mount, because the threat will not materialize for five years. And we will not deploy land-based interceptors in Europe, because our new plan is to deploy land-based interceptors in Europe.

Added to what would be the instability and potentially grave injury following upon the appearance of Iranian nuclear ICBMs are two insults that may be more consequential than the issue from which they arise. Nothing short of force will turn Iran from the acquisition of nuclear weapons, its paramount aim during 25 years of secrecy and stalling for time. Last fall, President Ahmadinejad set three conditions for the U.S.: withdrawal from Iraq, a show of respect for Iran (read: "apology"), and taking the nuclear question off the table.

We are now faithfully complying, and in September, after Iran foreclosed discussion of its nuclear program and President Ahmadinejad's chief political advisor predicted "the defeat and collapse" of Western democracy, the U.S. agreed to enter talks the premise of which, incredibly, is to eliminate American nuclear weapons. Even the zombified press awoke for long enough to harry the State Department spokesman, who replied that, as Iran was willing to talk, "We are going to test that proposition, okay?"

Not okay. When Chamberlain returned from Munich at least he thought he had obtained something in return for his appeasement. The new American diplomacy is nothing more than a sentimental flood of unilateral concessions—not least, after some minor Putinesque sabre rattling, to Russia. Cancelling the missile deployment within NATO, which the Russian ambassador to that body characterizes as "the Americans…simply correcting their own mistake, and we are not duty bound to pay someone for putting their own mistakes right," is to grant Russia a veto over sovereign defensive measures—exactly the opposite of American resolve during the Euromissile Crisis of 1983, the last and definitive battle of the Cold War.

Stalin tested Truman with the Berlin Blockade, and Truman held fast. Khrushchev tested Kennedy, and in the Cuban Missile Crisis Kennedy refused to blink. In 1983, Andropov took the measure of Reagan, and, defying millions in the street (who are now the Obama base), Reagan did not blink. In September, the Iranian president and the Russian prime minister put Barack Obama to the test, and he blinked not once but twice. The price of such infirmity has always proven immensely high, even if, as is the custom these days, the bill has yet to come.

A version of this essay appeared in the Wall Street Journal.