WASHINGTON/RIYADH - US President Barack Obama will seek to ease Saudi concerns that he is neglecting an old ally when he visits Riyadh on Friday, months after top Saudis objected to what they saw as a growing rapprochement between Washington and their rival Iran.
Rifts over Middle East policy came to a head last year when Washington worked with other powers to ease sanctions on Iran in exchange for concessions on its disputed nuclear programme, and backed away from air strikes on Tehran's ally Syria.
Senior figures in predominantly Sunni Muslim Saudi Arabia - which competes for influence in the region with Shi'ite Muslim power Iran - warned in October and November there might be a "major shift" away from Washington and Riyadh might "go it alone".
Obama, on his first trip to the world's top oil producer since 2009, is expected to try to clear the air after the rare public spat, and to find common ground on Syria's civil war and the Israeli-Palestinian peace process, said officials.
"He wouldn't be going to Saudi Arabia, he wouldn't be seeing the king, if he didn't feel the need to reassure them so that they don't go off on tangents that will in effect... not only not be productive but could be destructive," said Dennis Ross, Obama's former top Middle East adviser.
Although the United States is no longer a major importer of Saudi oil, Riyadh remains important to Washington for its cooperation in fighting al Qaeda and its influence with other Arab states, particularly as Obama pushes for an extension of US-sponsored Israeli-Palestinian peace talks.
For Riyadh's ruling princes, Washington has always been the ultimate guarantor of security, using its military clout to contain regional threats.
"The two countries have clear differences, but these do not really affect them working together towards the peace and security of the region," said Abdullah al-Askar, head of the foreign affairs committee in the Shoura Council, a body appointed by King Abdullah to advise on government policies.
However, the Saudis sharply faulted Obama for his response to the 2011 Arab uprisings, accusing him of discarding old allies who were ousted in revolts and of failing to stand up to their main regional rivals the Muslim Brotherhood and Iran.
In Syria, the Saudis see the civil war - pitting mostly Sunni rebels against President Bashar al-Assad, whose Alawite sect is an offshoot of Shi'ite Islam - as a pivotal battle in a wider struggle for Middle East influence with Iran.
Saudi Arabia has supported Syria's rebels while Tehran has backed Assad - echoing their support for opposing sides in other often sectarian conflicts in Iraq, Lebanon, Bahrain and Yemen.