RIYADH — Custodian of the Two Holy Mosques King Salman phoned US President Barack Obama on Monday to review the agenda for the Camp David summit with Gulf leaders, Saudi Press Agency said. The leaders agreed to work with other Gulf states “to build a collective capacity to address more effectively the range of threats facing the region and to resolve regional conflicts,” SPA said, noting that they agreed on the need for urgent humanitarian aid in Yemen. The two leaders also expressed hope that the 5 +1 talks with Iran will lead to preventing it from obtaining nuclear weapons. President Obama reiterated the US commitment to defend the security of the Kingdom from any external aggression. The two leaders looked forward to meeting soon for consultation and coordination over issues of common concern. They noted the strength and depth of the strategic and historical relations between the two countries since the historic meeting that took place between the late King Abdul Aziz and President Franklin D. Roosevelt. The US president welcomed the visit of Crown Prince Muhammad Bin Naif, deputy prime minister and minister of interior, and Deputy Crown Prince Muhammad Bin Salman, second deputy premier and minister of defense, on behalf of King Salman who is not participating in the summit due to his preoccupation with the humanitarian truce in Yemen and the opening of the King Salman Center for Relief and Humanitarian Work.