WASHINGTON -- The era of nonproliferation is over. During the first half-century of the nuclear age, safety lay in restricting the weaponry to major powers and keeping it out of the hands of rogue states. This strategy was inevitably going to break down. The inevitable has arrived.

The six-party talks on North Korea have failed miserably. They did not prevent Pyongyang from testing a nuclear weapon and entering the club. North Korea has broken yet again its agreement to reveal all its nuclear facilities.

The other test case was Iran. The EU-3 negotiations (Britain, France and Germany) went nowhere. Each U.N. Security Council resolution enacting what passed for sanctions was more useless than the last. Uranium enrichment continues.

When Iran's latest announcement that it was tripling its number of centrifuges to 9,000 elicited no discernible response from the Bush administration, the game was over. Everyone says Iran must be prevented from going nuclear. No one will bell the cat.

The "international community" is prepared to do nothing of consequence to halt nuclear proliferation. Which is why we must face reality and begin thinking how we live with the unthinkable.

There are four ways to deal with rogue states going nuclear: pre-emption, deterrence, missile defense and regime change.

Pre-emption works but, as a remedy, it is spent. Iraq was defanged by the 1981 Israeli airstrike, by the 1991 Gulf War (which uncovered Saddam's clandestine nuclear programs) and finally by the 2003 invasion, which ended the Saddam dynasty.

A collateral effect of the Iraq War was Libya's nuclear disarmament. Seeing Saddam's fate, Moammar Gaddafi declared and dismantled his nuclear program. And if November's National Intelligence Estimate is to be believed, the Iraq invasion even induced Iran to temporarily suspend weaponization and enrichment.

But the cost of pre-emption is simply too high. No one is going to renew the Korean War with an attack on Pyongyang. And the prospects of an attack on Iran's facilities are now vanishingly small. What to do?

Deterrence. It worked in the two-player Cold War. Will it work against multiple rogues? It seems quite suitable for North Korea, whose regime, far from being suicidal, is obsessed with survival.

Iran is a different proposition. With its current millenarian leadership, deterrence is indeed a feeble gamble, as I wrote in 2006 in making the case for considering pre-emption. But if pre-emption is off the table, deterrence is all you've got. Our task is to make deterrence in this context less feeble. Continued...