RIYADH - US President Barack Obama meets Saudi King Abdullah Friday as mistrust fuelled by differences over Iran and Syria overshadows a decades-long alliance between their countries.
Obama, who is due to arrive in Saudi Arabia late in the afternoon on a flight from Italy, is expected to hold evening talks with the monarch on a royal estate outside Riyadh.
Saudi Arabia has strong reservations about efforts by Washington and other major world powers to negotiate a deal with Iran on its nuclear programme.
It is also disappointed over Obama's 11th-hour decision last year not to take military action against the Syrian regime over chemical weapons attacks.
Saudi analyst Abdel Aziz al-Sagr, who heads the Gulf Research Centre, said Saudi-US relations are "tense due to Washington's stances" on the Middle East, especially Iran.
The recent rapprochement between Tehran and Washington "must not take place at the expense of relations with Riyadh," Sagr told AFP.
Sunni Muslim Saudi Arabia, long wary of Shiite Iran's regional ambitions, views a November deal between world powers and Iran over the latter's nuclear programme as a risky venture that could embolden Tehran.
The interim agreement curbs Iran's controversial nuclear activities in exchange for limited sanctions relief, and is aimed at buying time to negotiate a comprehensive accord.
But Sagr said "arming the Syrian opposition will top the agenda" during Obama's visit, his second since his election in 2009.
Analyst Khaled al-Dakhil spoke of "major differences" with Washington, adding that Obama will focus on easing "Saudi fears on Iran and on regional security."
Saudi Arabia, the largest power in the six-nation Gulf Cooperation Council, fears that a possible US withdrawal from the Middle East and a diplomatic overture towards Iran would further feed Tehran's regional ambitions.
Iranian-Saudi rivalry crystallised with the Syrian conflict: Tehran backs President Bashar al-Assad's regime, while several GCC states support the rebellion against him.
'Clearing the air'
Obama's stances towards events reshaping the region "have strained (Saudi-US) relations but without causing a complete break," said Anwar Eshki, head of the Jeddah-based Middle East Centre for Strategic and Legal Studies.
US security and energy specialist professor Paul Sullivan said Obama meeting King Abdullah could "help clear the air on some misunderstandings."