The summit comes on the heels of Obama's criticism of Saudi Arabia's regional role, which prompted a strong rebuke from the Saudi royal family.

In a recent interview with The Atlantic, Obama described Saudi Arabia and other allies as "free riders" on US foreign policy, and criticized what he saw as Riyadh's funding of religious intolerance.

Almost a year ago, in May 2015, Obama hosted leaders of Gulf nations at the White House and Camp David, the first meeting of the Gulf countries following a framework agreement on limiting Iran's nuclear program.

Except for Kuwait and Qatar, top leaders from four of the six-member GCC countries were absent from the 2015 summit.

With Iran a thorn in ties between Washington and its traditional Gulf friends, the U.S. side has tried to calm its allies before the visit.

"I don't think there can be any confusion about who is our partner in the region and who is not," said Obama's senior advisor for the Gulf Rob Malley.

However, the adivor talked about "a different relationship between the GCC and Iran," saying that Obama believed such a relationship is "good for the region and good for stability overall."

The White House said that Obama had spoken of a "cold peace" between Gulf states and Iran during talks with King Salman.

The president urged both sides to put aside their differences in order to focus on what he sees as a greater threat from the Islamic State.