Thurmont, Maryland (CNN) President Barack Obama, facing Persian Gulf countries deeply skeptical about his proposed nuclear deal with Iran, said Thursday that the U.S. would use military force if necessary to defend its Arab allies.

Obama had spent the day huddled with leaders from the region at his Camp David retreat, and emerged from their summit declaring that he was as committed as ever to protecting them from aggression, a reference to Iran.

A joint statement delivered at the end of the gathering declared that the U.S. will continue to "deter and confront external aggression against our allies and partners, as we did in the Gulf War," and that the U.S. Is ready would work with them to determine an appropriate response in the face of such aggression, "including the potential use of military force."

Anxieties about Iran's nuclear ambitions were far from abated by the end of the summit, and Obama acknowledged differences persist between himself and the oil-rich monarchies of the Gulf Cooperation Council bloc — Saudi Arabia, Kuwait, Bahrain, Oman, Qatar and the United Arab Emirates — with whom he met. But the leaders expressed optimism that enhanced defense ties would bring relations between the region and the United States to new levels.

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