Niall Ferguson:

True, after all that has gone wrong in Iraq, Americans are scarcely eager for another preventive war to stop another rogue regime from owning yet more weapons of mass destruction that don’t currently exist. It’s easy to imagine the international uproar that would ensue in the event of U.S. air strikes. It’s also easy to imagine the havoc that might be wreaked by Iranian-sponsored terrorists in Iraq by way of retaliation. So it’s very tempting to hope for a purely diplomatic solution.

Yet the reality is that the chances of such an outcome are dwindling fast, precisely because other permanent members of the U.N. Security Council are ruling out the use of force — and without the threat of force, diplomacy seldom works. Six days ago, Russian President Vladimir V. Putin went to Iran for an amicable meeting with President Mahmoud Ahmadinejad. Putin says he sees “no evidence” that Iran is trying to build nuclear weapons. On his return to Moscow, he explicitly repudiated what he called “a policy of threats, various sanctions or power politics.”

The new British prime minister, Gordon Brown, also seems less likely to support American preemption than his predecessor was in the case of Iraq. That leaves China, which remains an enigma on the Iranian question, and France, whose hawkish new president finds himself distracted by the worst kind of domestic crisis: a divorce.

By contrast, Washington’s most reliable ally in the Middle East, Israel, recently demonstrated the ease with which a modern air force can destroy a suspected nuclear facility. Not only was last month’s attack on a site in northeastern Syria carried out without Israeli losses, there was no retaliation on the part of Damascus. Memo from Ehud Olmert to George W. Bush: You can do this, and do it with impunity.

The big question of 2007 therefore remains: Will he do it?