Today, Britain and the West face a new Iranian hostage crisis. Reflecting on this and on President Ahmadinejad’s other actions and statements brings to mind George Orwell’s essay “Who are the War Criminals,” written during World War II.

Orwell criticized the appeasement of dictators during the 1930s by British political leaders. He disdained “the lies and betrayals of those years, the cynical abandonment of one ally after another … the flat refusal to believe that the dictators meant war even when they shouted it from the rooftops.”

At a Tehran conference on “A World Without Zionism” in late 2005, the Iranian president seemingly was shouting from the rooftops: “Our dear Imam [Ayatollah Khomeini] said that the occupying regime [Israel] must be wiped off the map and this was a very wise statement … we will eliminate this disgraceful stain from the Islamic world. …”

Around the world, these words – the first such declarations by a head of state since World War II – were condemned. But there also were eager apologists who said that the president was misunderstood, that, for example, he did not say “wiped off the map,” but “wiped away.” The gist of the statement, of course, is not lost in pedantic battles about translation and meaning. For Mr. Ahmadinejad did exactly what fascist dictators in the 20th century did before they acted on their words: He announced his plans, this time through the press of the global village.

Recently, the Iranian president met and expressed solidarity with officials in Sudan who have been carrying out genocide against non-Arabs in Darfur under the indifferent gaze of the so-called “world community.” Sudan’s president, Omar al-Bashir, architect of the genocide, has supported Iran’s drive for nuclear capacity. As if the symbolism of forging an alliance with a genocidal regime were not enough, Mr. Ahmadinejad declared to a group of Islamic scholars and officials in Khartoum that the “Zionists are the true manifestation of Satan,” and was greeted with chants of “God is Great!”

At home, the Iranian president has been busy developing nuclear power, claiming that nations have a “right” to such power for “peaceful means.” With the American troubles in Iraq – partly caused by Iranian support of terrorists – the “world community” standing by while genocide continues in Darfur, and the world’s dithering in the face of Iran’s nuclear development, one must acknowledge that Iran has achieved a victory of sorts.

The genocidal president of Iran meets the genocidaire government of Sudan, and we are, it seems, powerless. We watch, like the appeasers of the 1930s, wringing our hands, while the new fascists flaunt their success at genocide and proclaim their future murderous intentions with the added twist of developing the nuclear means to carry them out.

We have convinced ourselves that the Iranian president doesn’t really mean what he says. Mr. Ahmadinejad’s talk about the “right” of Iran to develop nuclear power is more convenient for the world community to believe than the possibility of war. Ironically, it is those who suggest that the dictators actually mean what they say – and in Sudan actually do so – who are seen as exaggerators leading us to war.

Similarly, when Hitler came to power, those who saw his danger were ignored and in some cases were treated as the “real problem.”

In the 1930s, the leader of Poland, Josef Pilsudski, accurately foresaw what Hitler intended for Poland and begged the great powers of Europe to intervene. For a war weary Europe, though, peace with Hitler and Mussolini was preferable to war, no matter what those fascists said.

For a war weary West, perhaps a nuclear Iran is inevitable, since the only way to stop Iran for sure would be to do as Israel did in 1981 with its pre-emptive strike against Iraq’s nuclear facility.

In contemplating such action, policies have to be based on what is possible not probable. September 11 was not probable but possible, and it became actual. The destruction of Chicago by a dirty bomb is not probable, but possible. Will it become actual? Are we hysterical for thinking so?

The Israeli historian, Benny Morris, made worldwide waves with an article in the Jerusalem Post and this paper postulating on the next Holocaust initiated by Iran with a nuclear first strike on Israel. His article created a firestorm of criticism, directed not at the Iranian president but against Mr. Morris for engaging in “scare-tactics.”

One cannot say precisely what should be done about Mr. Ahmadinejad’s crusade against Israel. There is serious talk in Israel about a pre-emptive attack. Israel’s consideration is based on the steely logic of thinking about what is possible, rather than what is probable, should Iran acquire a nuclear weapon.

Until we can institutionalize that calculation in dealing with threats, it is only a matter of time before those who benefit from our ambivalence translate their shouts from the rooftops into action. We civilized people may not want, or be able, to imagine a repetition of the 20th century’s barbarism, but only the very naïve would deny what could be the logical consequence of the genocidal rhetoric of today’s extremists.

Mr. Cushman, professor of sociology at Wellesley College, is the founding editor of the Journal of Human Rights.