Eye on Iran

They also agree on the use of sanctions to prevent Iran from pursuing a nuclear weapon, and they say military strikes remain an option to counter that threat. Both have pledged to support Israel if it is attacked.

Romney has said, if elected, his first foreign trip would be to Israel. He suggested Obama has alienated the Jewish state.

"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," said Romney.

Obama countered that the debate was on the eve of the largest U.S. and Israeli military exercise in history.

Overall, the candidates offer similar foreign policy proposals, said analyst Serwer.

"Beyond rhetoric, I think the major difference is on this question of arms to the Syrian rebels," said Serwer.

Syria conflict

Syrian security forces and opposition fighters have battled since the uprising against Syrian President Bashar al-Assad began in March of 2011. Romney favors providing weapons to the rebels.

"I want to make sure they get armed and they have the arms necessary to defend themselves, but also to remove Assad. But I do not want to see a military involvement on the part of our troops," said Romney.

Obama offers a more cautious response.

"For us to get more entangled militarily in Syria is a serious step, and we have to do so making absolutely certain that we know who we are helping; that we are not putting arms in the hands of folks who eventually could turn them against us or allies in the region," said Obama.