The assault on the U.S. consulate in Benghazi, Libya promises to play a big role in Monday's debate between President Barack Obama and former Governor Mitt Romney. But don't cringe: For all the silly gotcha moments about who cried "terror" and when, the Benghazi attack provides a chance for both candidates to address major concerns about their approaches to a chaotic world.

The first round of congressional hearings on the Benghazi assault have come and gone. But they didn't focus on the crucial question of the strategic implications of the assault. Does it mean the U.S. needs to involve itself deeper in the Arab Spring; pick favorites within the uprisings; or stand back as the the upheaval proceeds? Both candidates have said a lot about the incident and practically nothing about arguably the most important questions it raised.

Benghazi was a major departure for Obama. Whatever you think of his foreign policy, it's been devoid of single-shot, high-profile disasters. There haven't been hostage crises, Marine barracks or Khobar towers bombings, 9/11s or botched invasions. He's succeeded when his troops have executed missions like killing Osama bin Laden or freeing Americans from pirates; and secrecy conceals potential mistakes rising from his drone war. The result has been a veneer of competence.

But several aspects of his foreign policy have either skirted on the edge of disaster or risk tipping over into it, whether it's the surge and ensuing the drawdown from Afghanistan; or his inconsistent approach to the Arab Spring, where he'll intervene in Libya but not Syria. Indeed, Libya looked like the successful ouster of a dictator with no U.S. casualties, but it turned out the U.S. neglected the warning signs of Islamist resurgence in eastern Libya until it murdered four Americans.

Benghazi resonated because it pierced that veneer of competence. It's reasonable to wonder if there are about to be several Benghazis on Obama's watch, whether in the form of raided Mideast embassies or Taliban advances or an Iranian nuke. Obama's most urgent task in this debate is to explain why there won't be.

Obama began to make that argument last week by reminding voters that he ordered the raid that killed bin Laden: "We are going to hunt them down, because one of the things that I've said throughout my presidency is when folks mess with Americans, we go after them." But that's not an answer, unless Obama is prepared to accept avenging disasters, not preventing them. And militants in Benghazi suspected of involvement in the consulate attack are unimpressed by the bin Laden raid. Instead, Obama needs to explain how his approach to the Middle East adjusts to the assault and takes the region actively in a direction amenable to U.S. interests. Treating the attack as "non-optimal," as Obama said to Jon Stewart, is a cop-out, one that can reinforce an impression that Obama has been lucky, not wise – which Romney is sure to cultivate.

Romney arguably has an easier task. Now that he's narrowed the race, he just needs to seem like a credible commander-in-chief. But as Romney has sowed doubt about Obama's record, he's raised several about his own agenda. Thus far, Romney has yet to distinguish his geopolitical plans from Obama without seeming like he's out to start a whole new war.

For example: Romney has portrayed Iran's continued Uranium enrichment as a major Obama failure, and echoed Netanyahu's rhetoric of confrontation. But while Romney's rhetoric on Iran is bellicose – adviser Dan Senor last week emphasized keeping the "military option" available – his stated proposals for confronting Iran center around the economic sanctions that Obama has enacted. And while he criticizes Obama's "reset" with Russia, Romney doesn't acknowledge that the reset helped halt Russia's aid to Iran, which kept the Tehran regime from getting advanced air defenses and needed injections of cash. If Romney recognizes this tension in his agenda, he has yet to address how to overcome it.

That tension runs through many Romney foreign-policy proposals. He's tried to signal that he'd be tougher than Obama, but also that voters don't have to worry about electing a warmonger. He's often ended up blurring distinctions with Obama. On Afghanistan, for instance, he has endorsed Obama's exact strategy, even while criticizing it for weakness. Same thing with Syria: he's criticized Obama for staying aloof, but has stopped short of the critical step of arming the rebels, out of the same caution over inadvertently arming jihadists that Obama has exhibited. The exceptions have been Romney's calls for increased military spending and expanding the Navy – but he's provided few details for either.

Benghazi gives Romney a big opportunity to resolve these tensions. He's had two chances to signal how future Benghazis won't happen on his watch: first, a much-criticized attack on Obama within hours of the battle; second, a semantic criticism of Obama's statements on the attack at last week's debate. What Romney has yet to do is explain how his approach to the Arab Spring would move the Mideast in a pro-American direction. Romney has already tightened the race, so now he has to look like a competent commander-in-chief before sealing the deal with voters, and that's where Benghazi is a double-edged sword. If Romney's going to keep hammering Obama on Benghazi, at some point he has to unveil an alternative for avoiding them – deeper involvement in Arab civil wars? Greater opposition to their Islamic factions? – or he'll reinforce the impression that he's out of his depth on foreign policy.

Whatever the politics surround it, Benghazi is important. It revealed the U.S. doesn't understand the forces in the Mideast that the Arab Spring has unleashed, and lacks an understandable approach for dealing with them before they jeopardize American lives. Creating one is part of the foreign policy debate the country deserves. Whether Obama and Romney present that debate this evening is a different story.