Obama today left for an overnight trip to Saudi Arabia that has only two items on its public schedule: a meeting and a dinner with King Abdullah at his desert camp, a 30-minute helicopter ride from the capital of Riyadh.
Secretary of State John Kerry was travelling with Obama for what will be the president's third official meeting with the king in six years.
White House officials and Mideast experts say the Saudi royal family's main concern is Iran. They fear Iran's nuclear program, object to Iran's backing of the Bashar Assad regime in Syria and see the government of Tehran as having designs on oil fields in Saudi Arabia and Bahrain.
The Saudi anxieties have been building over time, according to Simon Henderson, a fellow at The Washington Institute, a think tank focused on Middle East policy.
"President Obama's U-turn on military action against Syria over its use of chemical weapons last summer only added to the concern, which has likely morphed into exasperation after recent events in Crimea, where the Saudis judge that President Obama was outmaneuvered by Vladimir Putin.