”The first requirement of a statesman is that he be dull,” said Dean Acheson.

During the final presidential debate, Mitt Romney was every bit the statesman. On foreign policy issues, he was well informed, earnest and gaffe-free. He refused to take the bait of hypothetical questions or Barack Obama’s continual attacks. “Well, of course I don’t concur with what the president said about my own record” was about as ferocious as it got. All evening, when Obama unleashed fireworks, Romney smothered them with a blanket.

We know from the second debate that Romney is pricklier than this. So his self-restraint was also evidence of a strategy. It amounted to a bold bet that boldness was not required. Romney set out to be relentlessly reassuring. Instead of pointing out contrasts, he systematically attended to his own credibility.

Romney often acted as if he were the only person on the stage — like a man trying to paint a self-portrait in the midst of a food fight. The image that emerged was a foreign policy moderate in tone and substance. Romney seemed a man who holds certain values but lacks disruptive projects and causes. He criticized Obama’s foreign policy mainly on implementation — pressure for Middle Eastern reform should have come earlier, Iranian sanctions should be tighter — rather than proposing an alternative grand strategy.

Romney summarized his own views as “principles of peace.” No direct intervention in Syria. No extension of the withdrawal deadline in Afghanistan. “We can’t kill our way out of this mess,” he insisted, unexpectedly pointing to the limits of drone strikes and special operations. In a deft, sophisticated move, Romney recommended a comprehensive soft-power strategy in the Middle East — economic development, better education, gender equality, the rule of law — as an alternative to later, messier interventions.

All this was an homage — perhaps a conscious one — to Ronald Reagan’s debate performance in 1980 against Jimmy Carter. Reagan was fighting a reputation for militarism and intemperance. In answer to his first question, he said, “I’m only here to tell you that I believe with all my heart that our first priority must be world peace, and that use of force is always and only a last resort, when everything else has failed, and then only with regard to our national security.” This reassurance was a hurdle cleared in his race to the presidency.

Romney employed the same argument, using some of the same words. Obama came into the foreign policy debate prepared to attack Romney as “wrong and reckless.” Every moment of Romney’s actual performance was a refutation of this argument. Obama’s incessant aggressiveness was a lingering reaction to the passivity of his first debate performance. For someone who believes navies and bayonets are equally outdated, Obama has a rhetorical tendency to fight the last war.

Romney publicly admitted the dirty little secret of foreign policy: continuity. Most foreign policy approaches are dictated by prudence and circumstance, not abstract ideology. It was Obama who ungenerously refused to recognize the same reality. It was Bush-era policies, he argued, that “got us into this mess.” Was he referring to the drone program he inherited? The status-of-forces agreement in Iraq he (rather incompetently) implemented? The doctrines of pre-empting threats and promoting democracy that he has reluctantly embraced? It is Obama’s foreign policy innovations — the “reset” with Russia, the “new beginning” with the Muslim world announced in his 2009 Cairo speech, the closing of Guantanamo Bay prison, the “daylight” between America and Israel in the peace process — that haven’t worked out so well.

There is a tension at the heart of Obama’s foreign policy, which no Republican candidate would find politically beneficial to point out. On the evidence of the final debate, Obama’s main foreign policy insight is the need for “nation-building here at home.” The killing of Osama bin Laden and the retreat from Afghanistan are presented as the last exertions of an overcommitted nation, ready to reduce defense spending and turn toward domestic needs. Yet promoting a just order in Middle Eastern chaos, or skillfully countering the rise of China, will require more engagement, and perhaps more resources. Al-Qaeda is not on its heels. The president himself seems to be leading America toward a messy confrontation with Iran. In these circumstances, the rhetoric of retrenchment is a failure of candor.

But this critique was beyond the scope of Romney’s debate strategy. If reassurance was enough, the hurdle is cleared.