Editor’s Note: Harry Kazianis, managing editor of the National Interest, sat down with Graham Allison, director of the Harvard Kennedy School’s Belfer Center for Science and International Affairs.

Harry Kazianis: To begin, please give us your thoughts on the recent U.S.-Russian agreement concerning Syria handing over its chemical weapons: Do you feel such an agreement will be successful? Do you believe Syria will comply with such a deal and is it technically possible considering the complexities of removing and destroying chemical weapons under normal conditions—not to mention a civil war?

Graham Allison: An arguably good place to be at this point—given the realistic menu of lousy options. While the likelihood of glitches and shortfalls is 100%, consider the bottom line. Can anyone identify a feasible alternative that has a higher likelihood of preventing future major attacks using chemical weapons or transfer to jihadists who could use them against the United States or our allies? I can’t think of one.

HK: A debate has brewed on the pages of TNI concerning Russia's influence in the Middle East. Do you feel Russia's power and influence over the Middle East has grown because of this agreement?

GA: Of course—and it would be disingenuous to argue otherwise. Putin has gone from being stigmatized, isolated, and indeed snubbed when Obama cancelled the scheduled bilateral Moscow summit a month ago, to being a kingmaker who got the U.S. and the world out of a corner—and is someone whom we are dependent on for the solution we are now pursuing. This has inexorably increased Russia’s credibility and influence in the region. The more important question, however, is whether Russia’s national interests in the region are contrary to those of the United States.

HK: Turning to Iran, there has been a great deal of speculation over a possible U.S.-Iran warming of ties. Have the stars aligned enough for an agreement over Iran's nuclear program that all sides can live with? How do you consider the prospects for a wider U.S.-Iran warming of ties going forward?

GA: Starting with objective factors, the stars are more aligned for an agreement constraining Iran’s nuclear program that will leave it verifiably short of an exercisable nuclear-weapons option (that is, an option to build nuclear weapons without being discovered in time for the United States or Israel to prevent it from reaching the goal line) than they have been at anytime recently.

But as I ask students in my course at Harvard, how many agreements are required between two nations? Three—and the first two are most difficult. First, the contending parties within Country A must agree about what they can accept; then the parties within Country B must do the same; and finally, there has to be some overlap in the zone of agreement between Country A and Country B.

Over the past decade, when Iran was prepared to accept an agreement that should, from the perspective of American interests have been acceptable, the U.S. was unwilling. When the U.S. was prepared to offer terms that should objectively have been acceptable to Iran, divisions there made an agreement impossible. Nonetheless, I am hopeful about the current alignment—though always cognizant of Samuel Johnson’s observation about second marriages: they represent “the triumph of hope over experience.”

HK: Moving to China, clearly the U.S.-China relationship is the world's most important—if not most complex. Where do you see the relationship going over the long term? As yourself have noted, the rise of a new power many times creates tensions with the existing current dominant power. In what ways do you feel the relationship can be managed in order to foster cooperation— or at the very least deter a dangerous competition now and in the future?

GA: The “Pax Pacifica” established by the U.S. after World War II has created a security and economic order in which the nations of the region, including China, have developed more successfully than at any time in their histories. Historians will remind us, however, that there is nothing unnatural about an increasingly powerful state demanding more say and greater sway in relations with nations that impact its interests.

How we understand this challenge is critical. If I can put on my professor’s cap for a moment, how we conceptualize relations between the U.S. and China over the next decade will be decisive. To help leaders recognize the magnitude of the challenge, I have proposed the concept of Thucydides’s Trap. As Thucydides pointed out about the Peloponnesian War in 5th century BC Greece, when a rising power challenges a ruling power, expect big trouble. As he said famously, “It was the rise of Athens and the fear that this inspired in Sparta that made war inevitable.” In a study I have done of the last five hundred years, in eleven of fifteen such cases, the result has been war. The point is not to be fatalistic, but to recognize the powerful structural forces at work when there is a rapid change in the relative power balance. If American and Chinese leaders perform no better than their predecessors in Classical Greece or Europe a century ago, historians of the twenty-first century will cite Thucydides in explaining the catastrophe that follows.

This means that in the years ahead, the biggest challenge for U.S.-China relations will not be the business of resolving one damned thing after another. It will be about each country developing a better understanding of how the other views the world, and about preparing themselves for the fact that massive adjustments of attitudes and actions will be required by both sides in order to avoid war.

HK: Finally, in the past, you have written extensively on nuclear terrorism. Do you still consider this a possible threat to the United States as well as globally?

GA: Absolutely. President Obama has said that nuclear terrorism is “the single biggest threat to U.S. security.” That was also the judgment of his predecessor, President Bush, and indeed of virtually everyone who has shouldered major responsibility for American national security in the decade since 9/11.

The good news is that Al Qaeda, the terrorist group that has had both the clearest intent to kill Americans massively and the organizational capacity to conduct major attacks, has been substantially weakened. The bad news is that there remains only one thing keeping terrorists, who have continued killing, but in smaller attacks, from killing thousands or tens of thousands in a single blow: despite repeated efforts, they have not succeeded in acquiring a nuclear bomb.

Image: U.S. State Department (Flickr)