Washington: US Secretary of State John Kerry is to meet his Saudi counterpart Foreign Minister Adel al-Jubeir in London today amid concerns over the dramatic breakdown in relations between his country and Iran.
On the eve of the trip, State Department spokesman Mark Toner said "they'll discuss a range of issues, bilateral and global issues, including obviously Iran and the ongoing crisis in Syria."
Washington and Riyadh have been close allies for decades but in recent months there has been mounting discord over the US diplomatic outreach to Iran, which Saudi Arabia sees as a dangerous enemy.
Kerry now spends more time on the phone with Iranian Foreign Minister Mohammad Javad Zarif than he does with al-Jubeir, most recently yesterday when he called Tehran five times to secure the release of captured US sailors.
The State Department, nevertheless, insists that it retains close ties with Saudi Arabia and remains critical of what it calls Iran's destabilising role in the region, illegal ballistic missile program and sponsorship of extremist groups.
Kerry talks in London will be a new occasion for Kerry to try to reassure Jubeir that Washington remains committed to their alliance, and to prepare the way for Syria peace talks later this month.
Saudi Arabia has taken a role in international efforts to broker an end to the Syrian civil war, coordinating a coalition of opposition and rebel groups that will send a joint negotiating team to Geneva on January 25.
For its part, Iran backs Bashar al-Assad's regime and the Lebanese Hezbollah militia which supplies some of the most effective forces defending his rule and which Washington regards as a terrorist army.
Saudi Arabia marked the New Year with a mass prisoner execution, killing a respected Shiite cleric alongside several alleged Sunni terrorists. Protests erupted in Shiite Iran, and the Saudi embassy was sacked.
Riyadh held Tehran responsible for the mob attack and broke off ties. Kerry has urged both sides not to escalate the situation and has sought assurances that the pair's spat will not undermine the Syrian talks.
The United States is also giving logistical and intelligence support to a Saudi-led coalition fighting Huthi rebels in Yemen, despite expressing concerns about the civilian toll of allied bombing.