Last week, Prime Minister Stephen Harper made a frightening claim about Iran. "I look at the rhetoric and the kind of philosophy that drives the Iranian regime, the kind of threats they have made to others in the world," he said, "and my deep concern about this regime is that, for the first time in history, we are facing a regime that not only wants to attain nuclear weapons but a regime that has, compared to virtually all other holders of nuclear weapons in the past, far less fear of using them."

No other leader has said anything remotely like that but Stephen Harper is clearly not alone in holding this view. Many people worry that Iran's leaders would incinerate Tel Aviv - even if doing so risks the immediate and total annihilation of Iran.

Are they right to worry? We can't answer that question with certainty. To do so, we would have to know what's in the minds and hearts of Iran's leaders, and to know how they will behave in the unpredictable circumstances of the future. No one can be sure of that. Not even Iran's leaders.

But Stephen Harper is certainly wrong about history. This is not the first time we have faced this situation.

Since the prime minister is in China now, he might want to ask his hosts about it.

The story begins in 1953, with the end of the bloody stalemate between the United States and China on the Korean Peninsula. The next year, the two countries clashed over possession of some islands in the Taiwan Strait, and Chinese dictator Mao Tse-tung responded by launching a program to develop nuclear weapons.

In 1958, there was another crisis in the Taiwan Strait. The Chinese ramped up their program, with the help of the Soviet Union. In 1959, as the Sino-Soviet relationship crumbled, the Soviets withdrew their support. But the Chinese pressed on.

In 1964, China detonated its first nuclear bomb.

China's entry into the nuclear club had little effect on the balance of power in Asia. It didn't destabilize the region. It did not cause nuclear proliferation. China did not become more aggressive. It did not engage in "nuclear blackmail." It did not give nukes to revolutionaries or terrorists. And it did not drop nuclear bombs on its enemies.

Some will say that was all perfectly predictable. Unlike the fanatics in charge of Iran today, the Chinese leadership was rational. It didn't use its nuclear weapons because it knew that doing so would invite obliteration. And Mao wasn't mad.

People who say that don't know history.

A year before China detonated its first atomic bomb, the influential American columnist Stewart Alsop wrote about "the madness of Mao Tse-tung." That was the standard perception at the time: The Soviets are at least rational. They can be deterred. But Mao? He's nuts.

Mao talked casually about nuclear war, even eagerly. It wasn't only survivable, Mao said. It was winnable.

"No matter what kind of war breaks out - conventional or thermonuclear - we'll win," Mao told Soviet leader Nikita Khrushchev in 1957. "We may lose more than 300 million people. So what? War is war. The years will pass and we'll get to work producing more babies than ever before."

Khrushchev came to despise and fear Mao. He called him "a megalomaniac warmonger." And more memorably, "a lunatic on a throne."

U.S. president John F. Kennedy shared that opinion. Relating Kennedy's view, an aide said that if Mao were to get the bomb it would likely be "the most significant and worst event of the 1960s."

As the dreaded event approached, U.S. officials carefully considered how to "strangle the baby in the cradle."

One operation would see the U.S. airlift a team of Taiwanese commandos to China's nuclear sites. Alternatively, the U.S. could equip the Taiwanese air force to carry out airstrikes. But neither of these attacks was likely to succeed, planners concluded. An American attack was necessary. And it would have to be big.

In one of the strangest moments of the Cold War, the Americans quietly asked the Soviets if they would consider a joint strike on China. The Soviets declined.

The planners knew that all these actions were dangerous. Their consequences couldn't be foreseen, let alone controlled. Unstoppable escalation into full-scale war was a real possibility.

And even if the Chinese facilities were destroyed, and the worst consequences avoided, the attack would only set back China's program for a number of years - while China would become more hostile and more determined to get nuclear weapons.

As historian Francis Gavin wrote, the perceived danger was far greater than anything we can imagine in the Middle East today. "China, with a population of more than 700 million in 1964, had already fought the United States in Korea; attacked India; and threatened Indochina, Indonesia, and Taiwan. It supported violent revolutionary groups around the world whose goals clashed with U.S. interests. Mao's internal policies had led to the deaths of millions of Chinese citizens, and he had already declared that nuclear war with the United States was not to be feared. In Mao's words, 'if the worse came to the worst and half of mankind died, the other half would remain while imperialism would be razed to the ground and the whole world would become socialist.' To the United States, such actions and statements made the People's Republic of China appear not only irrational but perhaps undeterrable."

Fortunately, some dissented. They included a U.S. State Department official named Robert Johnson. In a detailed study, Johnson argued it was very unlikely China would use nuclear weapons unless attacked.

Johnson also insisted that China's possession of nuclear weapons wouldn't dramatically alter the existing power politics.

Johnson's views were tacitly adopted by the new administration of Lyndon Johnson, not least because the White House didn't want to start a war in an election year. The U.S. shelved its attack plans.

China got the bomb. And Robert Johnson was proved right.

Of course Maoist China is not theocratic Iran. This history does not conclusively prove that Iran's acquisition of nuclear weapons would not end in tragedy.

But it is a warning. Overconfident judgments - like the prime minister's - can be as dangerous as any weapon.