President Barack Obama meets with Saudi King Abdullah at Rawdat Khuraim, Saudi Arabia, Friday, March 28, 2014. Rawdat Khuraim is a green oasis located 62 miles northwest of the capital city of Riyadh and King Abdullah's private desert encampment is located within Rawdat Khuraim. (AP Photo/Pablo Martinez Monsivais)

RIYADH, Saudi Arabia (AP) — President Barack Obama paid a visit Friday to the desert oasis of wary ally King Abdullah of Saudi Arabia, hoping to reassure the aging monarch who is nervously watching Washington's negotiations with Iran and other U.S. policy in the Middle East.

Obama's Marine One helicopter kicked up clouds of sand in his arrival at the king's desert camp outside the capital of Riyadh for a meeting and dinner with Abdullah. The president walked through a row of military guards to an ornate room featuring a massive crystal chandelier and took a seat next to the 89-year-old king, who was breathing with the help of an oxygen tank.

Secretary of State John Kerry sat at Obama's side for the visit that is the president's third official meeting with the king in six years.

Despite its decades-long alliance with the United States, Saudi's royal family has become increasingly anxious in recent years over Obama's nuclear talks with Iran and his tepid involvement in the Syrian civil war. During his evening meetings with the king, Obama's task was to reassure Saudi Arabia that the U.S. is not abandoning Arab interests despite troop withdrawals from Iraq and Afghanistan, greater energy independence back home and nuclear talks with predominantly Persian Iran.

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.

Deputy national security adviser Ben Rhodes told reporters aboard Air Force One on the flight to Saudi Arabia that the issues at the heart of Obama's meetings with Abdullah include Gulf security, Middle East peace, Syria, Iran and Egypt.

On Syria, Rhodes said Obama did not plan to make any specific announcements about additional assistance to opposition forces. He said the U.S. and Saudi Arabia have been working together closely to coordinate their assistance to the rebels.

Rhodes said that coordination has helped put the U.S. relationship with Saudi Arabia "in a stronger place today than it was in the fall when we had some tactical differences about our Syria policy."

"We are in a better place today than we were seven months ago," Rhodes said.

Obama angered Saudi officials by scrapping plans to launch a military strike against Syria, choosing instead to back a plan to strip Syrian President Bashar Assad of his chemical weapons.

Rhodes said Obama would update the king on the nuclear talks with Iran. He said Obama would also make the point that those negotiations do not mean U.S. concerns about other Iranian activities have lessened, including its support for Assad and Hezbollah, as well as its destabilizing activity in Yemen and the Gulf.

"Those concerns remain constant and we're not in any way negotiating those issues in the nuclear talks," he said.

Rhodes said human rights, including women's rights, would be on the agenda for Obama's meetings. But he said the U.S. has a broad range of security interests with Saudi Arabia that would be most prominent on the agenda.

"We've raised concerns around human rights issues, issues related to women's rights," Rhodes said, adding that the U.S. has to maintain "the ability to cooperate" with the Saudis on other issues.

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.

"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 longstanding allies," Henderson wrote this week. "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

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