Obama cited his record, saying al Qaida’s leadership had been “decimated,” and how his policies have allowed the United States to rebuild alliances and combat future threats.

Some of the other topics at Monday’s debate:

– Military spending: One way to show American strength, Romney has argued, is to beef up military capability. Before leaving for a pre-election recess, Congress agreed to set defense spending for fiscal 2013, the 12-month period that began Oct. 1, at about $519.9 billion, about the same as last year.

Automatic cuts planned to begin in January would shave about 9 percent to 10 percent from most Pentagon programs this year and $500 billion over 10 years. Romney says he’ll stop those cuts, but does not say specifically how he’d do that without increasing federal deficits.

Obama noted that the automatic cuts are “not something I proposed” and vowed they would not happen.

Romney reiterated his complaint that under Obama, the Navy is at its lowest number of ships since 1916.

Obama ridiculed the remark, saying the U.S. military needs have changed. "Well, Governor, we also have fewer horses and bayonets, because the nature of our military’s changed," Obama said. "We have these things called aircraft carriers, where planes land on them. We have these ships that go underwater, nuclear submarines."

– Iran: Obama vowed that as long as he’s president, Iran will not get a nuclear weapon. “A nuclear Iran is a threat to our national security and it’s a threat to Israel’s national security,” he said. Romney has said much the same thing

“I would tighten those sanctions,” he said.

Aside from putting greater stress on threatening military action, Romney hasn’t articulated a plan for dealing with Iran’s nuclear program that’s much different from Obama’s approach. That policy combines tightening sanctions and keeping a military option open while pushing for a diplomatic deal under which Iran would halt its enrichment of uranium.

While there have been U.S. sanctions on Iran for decades, Obama succeeded in winning Chinese and Russian support for additional U.N. measures and has coordinated a growing menu of harsher measures with the European Union. The combined steps, the toughest sanctions ever imposed on Iran, have severely slashed Iran’s oil export earnings, made it harder for Tehran to import nuclear-related materials, reduced the Iranian central bank’s access to hard cash and helped plunge the value of the rial by 80 percent in the last 10 months.

Iran has continued to expand its uranium enrichment program in defiance of U.N. resolutions. But Iranian leaders have in recent weeks called for the United States, the European Union, Russia and China to resume stalled negotiations on a diplomatic deal, and a new round is expect late next month.

– Iraq and Afghanistan: Romney has echoed Obama’s goal of withdrawing combat troops from Afghanistan by the end of 2014, but he said he’d let military commanders determine the pace. And Republicans have criticized Obama for failing to secure an agreement with Iraqi leaders to keep some peacekeeping forces in that country.

Romney has charged that the troop withdrawals were “based upon electoral expediency, not military requirement,” though polls have shown that most Americans support the move. Additionally, the American troop withdrawals from Iraq were required under a timetable negotiated by the Bush administration before Obama took office.

– Israel: “I will stand with Israel if it is attacked,” Obama pledged. “If Israel’s attacked, we have their back,” added Romney.

Obama rejected Romney’s characterization that in his first years in the White House he took an "apology tour" of the Middle East, and retorted by say that when Romney’s went to Israel this summer he went as a candidate.

"I didn’t take donors,” Obama said, of Romney’s traveling party. “I didn’t attend fundraisers" – a clear reference to Romney’s trip in which he was accompanied by casino magnate and donor Sheldon Adelson.

Obama said on his trip he went to the Holocaust museum "to remind myself the nature of evil and why our bond with Israel will be unbreakable."

– China. Some have argued China should be sanctioned for keeping the value of the yuan, its currency, too low, making products less expensive.

But the value of the yuan, the Chinese currency, is rising and China has signaled it is not interested in a trade dispute.

That’s not stopped the candidates from talking tough. The Obama campaign points to its record of bringing a high number of trade cases against China. “We’re going to insist China play by the same rules as everybody else,” he said Monday.

Romney countered by insisting, “On Day One, I will label them a currency manipulator.”

Jonathan S. Landay and Kevin G. Hall in Washington contributed.