If 2012 turned out to be the year of the "Cliff Hanger," what will 2013 bring? This column has written about the fiscal, strategic and civility cliffs. Alarmingly, the worst may yet to come: Consider the "Iranian cliff."

As Iran continues to enrich uranium and economic sanctions persist, a point of no return is fast approaching if the latter doesn't prevent the former.

Worse, that point may be determined by a small Israeli minority and not by the United States or other powers. Israeli Prime Minister Binyamin Netanyahu sees Iran's nuclear ambitions as an existential threat to his nation. Should Iran cross the so-called red line by enriching enough uranium to construct a bomb, Netanyahu has threatened an Israeli strike.

U.S. President Barack Obama says he has taken no option off the table including military force. But Obama also declared "containment" wasn't an option -- a strategic and grammatical contradiction of the first order. Hence, sometime this year, an Iranian cliff will materialize if sanctions don't yield constructive negotiations. Mishandled, that cliff will make the others look like anthills.

Arguments concerning the pros and cons of conventional air attacks against Iran's nuclear facilities are well understood. In sound bite form, proponents of an attack say that the very worst case is a nuclear-armed Iran. Hence and however dangerous, there is no alternative to a preventative military strike.

Opponents argue the reverse. As the West neutralized the Soviet Union's capability to eviscerate much of the world with its tens of thousands of nuclear weapons, Iran with a mere handful could easily be deterred and contained -- --although this language of the past must be translated into more acceptable wordage for today.

The consensus view is that conventional air attacks on Iran's nuclear sites would at best delay and could provoke retaliation as well as hasten acquisition of nuclear weapons by Tehran. Short of successful negotiations, Iranian self-restraint or an internal revolution that magically installs a friendly government, what then is the full range of options to prevent Tehran from obtaining and threatening to use nuclear weapons? The only certain ways to deny Iran's nuclear intentions permanently are through a nuclear strike or invasion and occupation. Are we prepared to consider either and think the unthinkable?

If Iran's threat is truly existential to Israel's survival or if an Iranian nuclear breakout sparked a destabilizing nuclear arms race with the danger of a regional nuclear war, why should the pre-emptive use of nuclear weapons or an invasion be automatically precluded from the options?

It is unlikely that Israel would ever and the United States never contemplate a nuclear attack. Regarding invasion and occupation, history matters. In 1978, the Pentagon produced the so-called Persian Gulf study headed by a mid-grade official, Paul Wolfowitz, later deputy secretary of defense. The study posited that if the Soviet Union invaded Iran driving south to seize its oil wells, what would be required to counter that assault. The conclusion was a U.S. force of about 300,000-400,000 troops.

Before his fall, the Iran Shah Mohammad Reza Pahlavi maintained a substantial military highly friendly to the West. Today, if Iran were to be invaded as Saddam Hussein attempted unsuccessfully, resistance would be massive. At least half a million troops would be needed to occupy and then pacify that country and its 80 million souls.

Barring some calamitous intervening event, making the case for an invasion with or without a supporting international coalition is beyond the reach of any U.S. administration.

Hence, given that conventional force provides no long-term solution to denying Iran nuclear weapons and could have disastrous consequences, invasion or nuclear pre-emption is unacceptable, the constructs of deterrence and containment albeit disguised with different words are the sanest and probably only policy choices. But would U.S. security guarantees be accepted? U.S. withdrawal from Iraq and Afghanistan would seem to confirm President John Kennedy's wry remark that the only thing worse than being an enemy of the United States was being a friend. And that was half a century ago.

My sense is that states such as Saudi Arabia and Turkey could accept a U.S. deterrent regime perhaps reinforced by British and French nuclear forces. Indeed, with skillful diplomacy that exploited an Iranian nuclear breakout, it isn't inconceivable that this common threat could force Saudi Arabia and Gulf states to forge closer ties with Israel -- reversing conventional wisdom that argues further proliferation is inevitable. While imperfect, a modified containment option is far better than the use of force, nuclear or otherwise, with potentially catastrophic effects that could set the oil rich region ablaze for decades.

If the way in which Washington negotiated the fiscal cliff is an indicator of things to come, we are in grave trouble. Make no mistake, the Iranian Cliff may well exceed our capacity to respond effectively or creatively.

(Harlan Ullman is chairman of the Killowen Group, which advises leaders of government and business, and senior adviser at Washington's Atlantic Council.)

(United Press International's "Outside View" commentaries are written by outside contributors who specialize in a variety of important issues. The views expressed do not necessarily reflect those of United Press International. In the interests of creating an open forum, original submissions are invited.)