With the Iraq war over and Afghanistan winding down, Iran is the most likely place for a new U.S. military conflict.
Obama says he'll prevent Iran from acquiring nuclear weapons. He hopes sanctions alongside negotiations can get Iran to halt uranium enrichment. But the strategy hasn't worked yet. Obama holds out the threat of military action as a last resort.
Romney accuses Obama of being weak on Iran. He says the U.S. needs to present a greater military threat.
Attacking Iran is no light matter, however. That is why neither candidate clearly calls for military action.
Tehran can disrupt global fuel supplies, hit U.S. allies in the Gulf or support proxies such as Hezbollah in acts of terrorism. It could also draw the U.S. into an unwanted new war in the Muslim world.
Masked Iranian army troops march in a military parade commemorating the start of the Iraq-Iran war 32 years ago, in front of the mausoleum of the late revolutionary founder Ayatollah Khomeini, outside Tehran, Iran, Friday, Sept. 21, 2012. (AP Photo/Vahid Salemi)