US Secretary of State John Kerry arrived in Abu Dhabi on Monday to meet his Emirati counterparts on efforts to build a Syrian opposition coalition to lead peace talks with the Damascus regime.
Kerry has scheduled meetings with Abu Dhabi Crown Prince Sheikh Mohamed bin Zayed al-Nahyan and United Arab Emirates Foreign Minister Sheikh Abdullah bin Zayed al-Nahyan.
US officials said he also hoped to meet Saudi officials.
The American envoy is spearheading international efforts to halt Syria's four-and-half-year civil war by putting opposition and rebel factions around a table with Bashar al-Assad's government.
Major powers with an interest in the conflict have set an ambitious target date of January 1 for talks and a ceasefire to begin, but the participants have yet to be identified.
Saudi Arabia, which supports some of the Sunni rebel forces active on the battlefield, has taken charge of assembling a motley coalition of exile groups, armed factions and Islamist parties.
These would exclude the Islamic State jihadist group and the Al-Qaeda affiliated Al-Nusra Front.
However, they could draw in groups such as Al-Nusra's powerful Islamist ally Ahrar al-Sham.
The hope is that if a broad enough "moderate" opposition coalition can enter a ceasefire and peace negotiations with Assad's loyalists, a path to a political transition an be found.
Meanwhile, the various local and international armies who have been drawn into the conflict will be able to focus their fire on the hardline jihadists like the Islamic State group.
Monday's one-day stopover in Abu Dhabi is the first leg of a Middle East tour that will also take Kerry to Israel and the Palestinian territories on Tuesday for talks on an upsurge of violence there.