Expressions from the third presidential candidates' debate, focused on Middle East policy.

U.S. President Barack Obama and Republican challenger Governor Mitt Romney sparred on Monday over who was Israel’s strongest defender, but both agreed that a military strike over Iran’s nuclear program must be a “last resort.”

Tehran’s nuclear program, which the West suspects is for developing weapons and that economic sanctions have so far failed to stop, is almost certain to be among the top foreign policy challenges facing the next president.

During the candidates’ third and final debate in Boca Raton, Fla.—which centered on foreign policy—Romney challenged the effectiveness of Obama’s Iran policy, saying his perceived weakness has strengthened the ayatollahs’ resolve. “They have looked at this administration and felt that the administration was not as strong as it needed to be,” he said. “I think they saw weakness where they had expected to find American strength.”

“We’re four years closer to a nuclear Iran. We’re four years closer to a nuclear Iran,” Romney continued. “And—and we should not have wasted these four years to the extent they’ve—they continue to be able to spin these centrifuges and get that much closer.”

Obama, meanwhile, accused Romney of rushing to conclude that a military strike was necessary. “The disagreement I have with Governor Romney is that, during the course of this campaign, he’s often talked as if we should take premature military action,” Obama said. “I think that would be a mistake, because when I send young men and women into harm’s way, I always understand that is the last resort, not the first resort,” he said.

Romney responded that “We need to increase pressure, time and time again, on Iran because anything other than … a solution to this … which stops this, this nuclear folly of theirs, is unacceptable to America.”

“And of course, a military action is the last resort. It is something one would only … consider if all of the other avenues had been … tried to their full extent,” he said.

The candidates did not offer sharply contrasting policies to address the Iranian challenge. They agreed on the need for tough economic pressure—and for safeguarding Israel.

“If Israel is attacked, we have their back, not just diplomatically, not just culturally, but militarily,” Romney said.

Obama said, “I will stand with Israel if they are attacked.”

The president later called Israel “a true friend and our greatest ally in the region,” and said Israel and the U.S. maintain “unprecedented military and intelligence cooperation, including dealing with the Iranian threat.” Obama went on to say that a nuclear Iran would be a national security threat to the U.S. He stressed he would not let Iran obtain a nuclear bomb so long as he is president and would not let Iran “perpetually engage in negotiations that lead nowhere.”

Obama and Romney did not say what they would do if Israel conducted a unilateral strike on Iran. Pressed by the moderator on how he would react if Israel were to launch a unilateral strike against Iran, Romney said, “Our relationship with Israel, my relationship with the prime minister of Israel [Benjamin Netanyahu] is such that we would not get a call saying our bombers are on the way or their fighters are on the way.” Romney and Netanyahu both worked for a Boston-based consulting firm in the 1970s.

Romney slammed Obama for sidelining the relations with Israel as part of the effort to curry favor with other Middle East players, evident by what the governor called an “apology tour.”

“You went to the Middle East and you flew to Egypt and to Saudi Arabia and to Turkey and Iraq. And by [the] way, you skipped Israel, our closest friend in the region, but you went to the other nations,” Romney said. “And by the way, they noticed that you skipped Israel. And then in those nations and on Arabic TV you said that America had been dismissive and derisive. You said that on occasion America had dictated to other nations. Mr. President, America has not dictated to other nations. We have freed other nations from dictators.”

Romney also attacked Obama for not acting to shore-up relations with Israel even after 38 members of Congress had sent him a letter urging him to do so. “They asked him, please repair the tension—Democrat senators—please repair the damage,” Romney said.

Obama said his administration and he personally consider Israel’s security paramount, in part owing to the impression left by his visit there as a candidate in 2008. “I went down to the border town of Sderot, which had experienced missiles raining down from Hamas. And I saw families there who showed me where missiles had come down near their children’s bedrooms, and I was reminded of what that would mean if those were my kids, which is why, as president, we funded an Iron Dome program to stop those missiles.”

Reacting to the debate, Republican Jewish Coalition (RJC) Executive Director Matt Brooks said Romney demonstrated “his knowledge of foreign policy issues and his understanding of the nature of our allies and foes on the global stage.” Romney “made it clear that in order for the U.S. to fulfill its role in the world, we must first be strong—economically, militarily, and diplomatically,” according to Brooks.

“[Obama’s] policies over the last four years have weakened us,” Brooks said in a statement. “Romney’s plans to grow the economy and get people back to work will strengthen America at home and in the eyes of the world.”

National Jewish Democratic Council (NJDC) President David A. Harris said Obama’s “statements of unequivocal support for Israel” during the debate were “just the latest demonstration of this President’s rock-solid commitment to the Jewish state and its security.”

“For pro-Israel voters, only one candidate in this race has a proven record when it comes to standing up for Israel’s security, and those voters were reminded of that tonight,” Harris said in a statement. “President Obama showed—in this exchange, and throughout the evening—why and how he has stewarded the U.S.-Israel relationship and the effort to halt Iran so powerfully and with maturity, seriousness and confidence over the past four years.”