Which current head of state is the greater threat to world peace – Mahmoud Ahmadinejad or George W. Bush? Even to ask this question is absurd and insulting. In Europe, however, far more attention is paid to what the United States might do about Iran’s nuclear ambitions than to what Iran is actually doing. Here, it is taken for granted in establishment circles that the real diplomatic imperative now is to stop the Bush administration bombing Iranian nuclear facilities rather than to stop Iran using those facilities to obliterate Israel.

So what is going on in Iran? The news from Teheran this week is chilling. On Tuesday the Iranian president spoke in the holy city of Mashhad before crowds chanting “death to America” and Allahu akbar (“God is great”). As they raised their fists in the air, Mr. Ahmadinejad claimed that Iran had “joined the club of nuclear countries” because its scientists had succeeded in enriching uranium. He swore that, despite an ultimatum from the United Nations Security Council which expires at the end of April, Iran would not back down “one iota,” adding: “Enemies can’t dissuade the Iranian nation from the path of progress that it has chosen.”

This, of course, is just the latest turn of the screw. Mr. Ahmadinejad is a former Revolutionary Guard who is dedicated to messianic aims, including the annihilation of Israel and the extension of the Iranian revolution to the entire Muslim world and beyond. But he speaks for the regime of the Islamic Republic, including its Supreme Leader, Ayatollah Khamenei.

And we know that Mr. Ahmadinejad means business. At Netanz alone, one of dozens of nuclear plants under construction all over Iran, some 50,000 centrifuges will soon be working day and night to manufacture enough enriched uranium to build up to ten nuclear weapons a year. Some would be mounted on missiles capable of menacing not only six million Israelis and hundreds of thousands of U.S. troops, but the entire Middle East. Nuclear weapons might also be given to Iranian-controlled terrorist organizations, such as Hezbollah. It is not just the White House that is worried; the International Atomic Energy Agency has also voiced its deep concern.

The impact of this second “Islamic bomb” (following Pakistan’s) is already being felt throughout the region. Saudi Arabia is reported to have a secret nuclear program of its own in response to the Iranian threat, while major powers such as Turkey and Egypt are unlikely to stand idly by. Israel, as the most likely target, is agonizing about whether anything can be done before it is too late.

Yet to listen to the BBC interviewing Seymour Hersh of the New Yorker this week, you’d think that the regime with a universal mission to impose its apocalyptic ideology by force, regardless of the cost in human lives, was not Iran, but the United States.

Mr. Hersh is presented by the BBC as a paradigm of objectivity: The title “investigative reporter” is accorded the kind of reverential solemnity once reserved for popes and presidents. But in his interview, he abandoned any pretense of neutrality. His rambling article boils down to a simple, one-sided thesis: The Bush White House has refused to rule out the option of tactical nuclear strikes to destroy Iran’s underground nuclear facilities. He quotes a Pentagon adviser who warns that the neoconservative elements in the administration are a “juggernaut that has to be stopped.” It is Mr. Bush, not Mr. Ahmadinejad, who is depicted in Hersh-speak as “messianic.” The military top brass are appalled. So are America’s allies.

If there is so much opposition in Europe, with even the British said to consider it a “very bad idea,” why does the president insist on keeping this hypothetical nuclear option on the table? At this point Mr. Hersh lowered his voice to sound even more conspiratorial. There was, he confided, a wild card right here in Britain: “Tony Blair.” The British prime minister’s thinking was so close to the president’s that the two might just do the unthinkable and press the nuclear button.

The BBC has never forgiven Mr. Blair for instigating the Hutton inquiry, which condemned the corporation for alleging that the prime minister had deliberately lied about Saddam Hussein’s weapons of mass destruction. That inquiry led to the resignations of the BBC’s two most senior executives. Since then, the BBC has been much more cautious in its editorializing, but its culture has not changed. Now, with the help of Mr. Hersh, the BBC has the opportunity to portray Messrs. Bush and Blair as a couple of Dr. Strangeloves, hell-bent on nuking millions (or was that billions?) of Muslims. Donald Rumsfeld and other US officials trashed the Hersh conspiracy theory, but the BBC paid no attention to their denials.

It is, of course, very easy for the likes of the BBC to report from Washington, where information and access are freely available. Iran is another story, and a much more difficult one to report. Iranian dissidents, mainly students and academics who have protested against the regime, are being crushed by Mr. Ahmadinejad. In order to consolidate his totalitarian aims, the Iranian president is sending gangs of Islamist “volunteers” into campuses to intimidate opponents. They hold bizarre “martyr’s ceremonies” at which soldiers from the Iran-Iraq war are buried on campus as part of a systematic purge of the universities. Professors who do not show the requisite fanaticism are sacked; nonconformists are imprisoned, tortured or murdered.

The thought of this incontestably evil regime wielding nuclear weapons is enough to make even Europeans feel uncomfortable. As this newspaper reported back in February, a poll in France, Britain, Germany, and Austria carried out by the European Foundation for Democracy found that majorities in these countries were worried about the prospect of Iran acquiring nuclear weapons, did not believe Iranian denials and that between 46% in Germany and 74% in France supported “limited military action by NATO to destroy Iran’s ability to make nuclear weapons.”

The BBC is too busy interviewing critics of the Bush administration to report the Iranian purge, so eerily reminiscent of Hitler’s Germany. In Hitler’s Political Testament, the Nazi dictator charged his successors with “merciless resistance to the universal poisoner of all peoples, international Jewry.” Hitler’s rhetoric is echoed by Mr. Ahmadinejad every time he addresses his Nuremberg-style rallies. If, as Seymour Hersh alleges, Mr. Bush regards the Iranian president as another Hitler, he is not far from the mark. Mr. Ahmadinejad is, in effect, devoting the entire resources of the Iranian state to carrying out the terms of Hitler’s will. Only one country can stop him: the United States. That is why, if the worst comes to the worst, Mr. Blair will stand by Mr. Bush against Mr. Ahmadinejad, the man who wants to make himself Hitler’s heir.