ROME — President Barack Obama is leaving the European continent and shifting his attention from an Eastern European power play to the complicated religious and tribal politics of the Middle East.

After four days spread across European capitals in the Netherlands, Belgium and Italy, Obama is off to Saudi Arabia to reassure Arab allies that despite troop withdrawals from Iraq and Afghanistan, greater energy independence back home and nuclear talks with predominantly Persian Iran, the United States is not abandoning the Arab world.

Obama’s overnight trip has only two items on its public schedule: a meeting and a dinner with King Abdullah at his desert camp.

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.

White House deputy national security adviser Ben Rhodes identified the points of anxiety in the relationship when he described Obama’s agenda for the trip last week as: “Our ongoing support for Gulf security, our support for the Syrian opposition where we’ve been very coordinated with the Saudis, the ongoing Middle East peace discussions, as well as both the nuclear negotiations with Iran but also our joint concern for destabilizing actions that Iran is taking across the region.”

The Saudi anxieties have been building over time, according to Simon Henderson, a fellow at The Washington Institute.

“Ever since Washington withdrew support for President (Hosni) Mubarak of Egypt in 2011, Abdullah and other Gulf leaders have worried about the reliability of Washington’s posture toward even long-standing allies,” Henderson wrote. “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.”

The technological advances that have increased oil and gas production in the United States have also made Gulf states nervous, said Tamara Cofman Wittes, a senior fellow at the Brookings Institution and director of its Saban Center on Middle East Policy.

“A lot of people in the region, I think, are naturally asking themselves what America’s energy independence means for America’s willingness to invest in the security of energy and supply from the Gulf,” she said.