As US President Barack Obama begins his second term, he will have to devote much of his attention to figuring out how to get America's domestic finances in order.
But foreign-policy issues loom large as well, and, notwithstanding the ongoing conflict in Syria and the possible spread of war across Africa's Sahel region, the consensus in Washington is that 2013 will be the "year of decision" on Iran.
Obama began his first administration with an offer to engage with the Islamic Republic; as he memorably put it in his first inaugural address in 2009, "We will extend a hand if you are willing to unclench your fist." He repeated that commitment, although much more obliquely, in his second inaugural address: "We will show the courage to try and resolve our differences with other nations peacefully- not because we are naive about the dangers we face, but because engagement can more durably lift suspicion and fear."
"Obama has repeatedly committed himself to the goal of turning the world in the direction of "global zero"- a world without nuclear weapons."
As the American scholar and activist Hussein Ibish recently argued, Obama has appointed a cabinet designed to give him maximum room to negotiate a deal with Iran.
In particular, naming military veterans as Secretary of State and Secretary of Defense will provide him with valuable domestic political cover for an agreement that would inevitably require lifting sanctions on Iran and almost certainly recognising its right to enrich uranium at a low level of concentration.That should signal to Iran's rulers not only that the US is serious about a deal, but also that whatever the US offers is likely to be the best deal that they can get.
The Obama administration has assembled an extraordinary coalition of countries to impose economic sanctions that are having a demonstrable effect on the price and availability of goods in Iran and on the ability of even powerful institutions, such as the Revolutionary Guard, to do business.
But coalitions do not hold together forever, and the pain of sanctions often cuts both ways, affecting buyers as well as sellers. Countries like South Korea and Japan, for example, have curtailed their imports of Iranian oil only reluctantly; countries like China and Russia rarely play straight on sanctions in the first place.
Moreover, Obama can threaten that "all options are on the table" only so many times without losing credibility with the Iranians and other countries in the Middle East.
As Brookings Institution foreign-policy expert Suzanne Maloney points out, countries in the region and beyond are already dismayed at the lack of US leadership concerning Syria. If the US gives negotiations one more serious try (a credible offer and a genuine willingness to engage), gets rebuffed, and then does nothing, it will effectively declare itself a paper tiger. At that point, the sanctions coalition will most likely disintegrate amid a much broader loss of confidence in US leadership.
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The US has thus painted itself into a corner. Former US National Security Adviser Zbigniew Brzezinski recently argued strongly against military action, proposing, instead, a strategy that would continue sanctions and extend deterrence. Like US policy toward the Soviet bloc during the Cold War, "An Iranian military threat aimed at Israel or any other US friend in the Middle East would be treated as if directed at the United States itself and would precipitate a commensurate US response."
I can certainly see the wisdom in Brzezinski's approach. But Obama has marched the US and its allies too far down the current path. Moreover, and crucially, Brzezinski forgets that Obama's determination to stop Iran from acquiring a nuclear weapon does not stem only from his concern for Israel's security or the stability of the wider Middle East.
Obama has repeatedly committed himself to the goal of turning the world in the direction of "global zero"- a world without nuclear weapons.
He believes (as do former Secretaries of State Henry Kissinger and George Shultz, former Secretary of Defense William Perry, and former Senator Sam Nunn) that unless the world finds a way to live without nuclear weapons, we will find ourselves in an international system in which 30-50 states possess them, raising the danger of accidental or deliberate launch to an unacceptably high level.
Convincing great powers to eliminate their nuclear arsenals might seem as politically fanciful as pushing gun-control legislation through the US Congress, but on that issue, too, Obama has made clear that he is willing to try.
However logical or attractive a containment policy might be, and however disastrous the consequences of bombing are likely to be, Obama's commitment to realising global denuclearization as part of his legacy implies that he will not allow another country to acquire a nuclear weapon on his watch, as his predecessors allowed India, Israel, North Korea, and Pakistan to do. Thus, the stakes for both the US and Iran are very high.
Other countries would do well not to underestimate Obama's resolve; governments that have relations with Iran should emphasise that the time to make a deal is now.
And countries like Turkey and Brazil (and perhaps India and Egypt) could play a useful role by devising face-saving ways for the Iranians to meet the international community's demands, together with longer-term alternatives for fuel enrichment that would be consistent with reducing the global nuclear threat. America's allies, in turn, must be prepared to close ranks with it on both the outlines of a deal and the willingness to strike militarily.
The art of statecraft is not to choose between war and diplomacy as if they were mutually exclusive alternatives, but to understand how they fit together. In the case of Syria, the West has repeatedly called for diplomacy while ruling out any military action, with predictably bad results. The US will not make that mistake with Iran.
Anne-Marie Slaughter, a former director of policy planning in the US State Department (2009-2011), is Professor of Politics and International Affairs at Princeton University.
A version of this article previously appeared on Project Syndicate.
The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.