MICHAEL REYNOLDS / AFP / GETTY IMAGES Moderator Bob Schieffer listens to Republican presidential candidate Mitt Romney and President Barack Obama during the third presidential debate at Lynn University in Boca Raton, Fla., Oct. 22, 2012.

For anyone tired of war and suspicious of overseas American adventures, Monday night’s debate was probably heartening. The tonal emphasis was entirely on prudence and peace. “We don’t want another Iraq or Afghanistan,” Mitt Romney said, later adding: “Our purpose is to make sure the world is more — is peaceful. We want a peaceful planet.” Barack Obama boasted about ending the war in Iraq and his 2014 exit date from Afghanistan. “I think we all recognize we got to do some nation building here at home,” Obama explained. Both candidates made clear that they won’t get directly involved in Syria’s civil war.

Indeed, a causal viewer might have overlooked one simple fact that overwhelms all this gentle talk: Both Obama and Romney are poised to start a new war in the Middle East as soon as next year.

(VIDEO: Time Explains: The Red Line on Iran)

We are speaking here, of course, about Iran. Last night both Romney and Obama vowed, yet again, to prevent Tehran from acquiring a The Bomb. “As long as I’m president of the United States, Iran will not get a nuclear weapon,” Obama declared. Said Romney: “There’s no question but that a nuclear Iran, a nuclear-capable Iran, is unacceptable to America.”

Yes, the candidates are clear, as Romney said Monday night, that military action would be a “last resort,” after all diplomatic and economic options are exhausted. (The candidates tend not to mention the quiet covert war already underway.) And yes, the current sanctions are taking a real toll, and perhaps making Tehran newly open to a deal. Let’s hope so.

But sanctions, diplomacy and covert action may very well fail to prevent Iran’s march to a nuke. Estimates of how long it would take Iran to build a bomb vary substantially, and Obama and Romney describe different “red lines” that would trigger military action. (Romney’s is a step earlier than Obama’s.) But with Benjamin Netanyahu hinting that Israel may run out of patience by next summer, America could be bombing Iranian soil before the 2013 World Series. (The U.S. isn’t tied to Israel’s timetable, but there’s a good case that if Israel is prepared to strike, America may as well join or do it for them–we’re more likely to inflict substantial damage, and will incur major blowback from an Israeli strike anyway.)

(MORE: Whether It’s Romney or Obama, U.S. Will Consider Direct Talks with Iran)

If we do attack Iran, the potential consequences are unpredictable but scary to contemplate. Hezbollah and Hamas could open war on Israel. Iran could try to close off oil shipping lanes. Either one could force an American response. This Harvard Belfer Center study of a possible Iranian closure of the Strait of Hormuz imagines that “U.S. attempts to reopen the waterway likely would escalate rapidly into sustained, large-scale air and naval operations during which Iran could impose significant economic and military costs on the United States.”

Clearly, both Romney and Obama want to give peace a chance. But they are also entirely prepared for war with Iran. And you don’t have to think an Iranian bomb is no big deal to say that, even after three prime-time debates, it doesn’t feel like they’ve adequately warned America about what that could mean.

MORE: The Election’s Real Foreign Policy Issue: War with Iran