Leaders of Gulf nations unnerved by Washington's nuclear talks with Iran and Tehran's meddling across the Mideast look to President Barack Obama to promise more than words and weapons at Thursday's Camp David summit. They want commitments from Obama that the United States has their backs at a time when the region is under siege from militants, Syria continues to unravel, Iraq is volatile and Yemen is in chaos. "I think we are looking for some form of security guarantee, given the behavior of Iran in the region, given the rise of the extremist threat," said Yousef al-Otaiba, the United Arab Emirates' ambassador to the United States. "In the past, we have survived with a gentleman's agreement with the United States about security. I think today, we need something in writing. We need something institutionalized."

Weapons sales, a renewed call for a coordinated missile defense system, more joint military exercises, better cooperation on cybersecurity, as well as maritime or border security and making the countries' defense systems work in concert will be on the table. "I don't believe there's a single country (in the council) that doesn't think a defense shield for the region is a bad idea," Otaiba said. "The challenge is how do you turn on a regional defense system when different countries are purchasing different equipment and at different paces? How do you link it? How do you get the radars to talk to each other?" A high-level Saudi official told AP in Riyadh that his country wants a defense system and military cooperation similar to what the U.S. affords Israel. The official, who spoke on condition of anonymity because he wasn't authorized to disclose details of the Saudis' wish list at the summit, said they also want access to high-tech military equipment, missiles, planes and satellites, as well as more technology and training cooperation with the U.S.

The U.S. and five other nations are working to complete a deal intended to stop Iran's pursuit of nuclear weapons in exchange for easing penalties that are choking the Iranian economy. The White House says the Gulf countries would be better off with an agreement that blocks Iran's path to an atomic weapon. But the nuclear deal is not the only source of unease.

Arab allies feel threatened by Iran's rising influence and they fear a nuclear pact will embolden Tehran. They worry that the deal would unlock billions of dollars that Iran might decide to use to further intrude in countries or support terrorist proxies.

Saudi Arabia's King Salman will not attend the summit, his foreign minister, Adel al-Jubeir, said. He said the summit coincides with a humanitarian cease-fire in the conflict in Yemen. He said Nayef would lead the Saudi delegation and the king's son, Deputy Crown Prince Mohammed bin Salman, who is defense minister, will also attend. Obama had planned to meet Salman one-on-one a day before the gathering of leaders at the presidential retreat but the White House did not take his decision to skip the summit as a sign of any substantial disagreement with the U.S.