US Secretary of State John Kerry said Saturday that he was confident that Syrian peace talks would go ahead despite wrangling over who should represent the warring country's fractured opposition.
"We are confident that, with a good initiative in the next day or so, those talks can get going and that UN representative Staffan de Mistura will be convening people," Kerry said after meeting Gulf foreign ministers in Riyadh.
The talks, originally slated to start Monday, are expected to be delayed, with Saudi Arabia, Turkey and Russia - as well as Syrian rebels and Kurds - at loggerheads over who should be included in the opposition delegation.
The US and Russia met this week, trying to iron out differences, but they did not reach full accord.
The first round of proximity talks between government and the opposition would immediately be followed by a meeting of the International Syria Support Group, which includes foreign powers, Kerry said, stressing the need to maintain forward momentum.
Kerry's visit to Saudi Arabia also aims at reassuring Gulf allies wary of Iranian involvement in Syria, especially following the lifting of sanctions on Iran tied to its recently certified nuclear deal.
Saudi Arabia is worried about a less isolated Iran developing closer ties to the US. Iran, along with Russia, are the main supporters of al-Assad.
The talks in Riyadh came as part of a US diplomatic push that also saw Vice President Joe Biden meeting Turkey's top leaders.
Turkey, like Saudi Arabia, has influence over Sunni Arab rebel groups, including some hardline Islamic factions, and the US is looking for support from its allies in putting together a viable opposition delegation.
Complicating matters, Russia, the main backer of the Syrian government in the country's civil war, considers Islamist rebel groups to be terrorists and argues they should be excluded, a demand Ankara and Riyadh do not accept.
At the same time, the participation of the Kurdish-led alliance, which controls much of northern Syria, has become another stumbling block, with Russia backing their inclusion while rebels and Turkey reject it.
The Kurds are the main US ally on the ground in pushing back the Islamic State in Syria. Turkey fears their links with Kurdish PKK fighters on its own soil and rebels want the Kurds to fight Syrian government forces, highlight the complex web of interests.
Analyst Andrew Tabler of the Washington Institute for Near East Policy said the Geneva talks were unlikely to end the conflict as the government and rebels remained committed to hardline positions.
However, the talks could deliver on short-term objectives.
"The main issue they will want to talk about is ceasefires and the modalities of ceasefire,” Tabler said. "I think the [US'] expectation is just to de-escalate this conflict."
Biden, in Istanbul, said that he and Turkey's Prime Minister Ahmet Davutoglu agreed on the need to support Sunni Arab groups in Syria fighting Islamic State along the Syrian-Turkish border. Turkey has recently been aiding these factions.
The US vice president also backed Turkey's position that the armed Kurdistan Workers' Party (PKK) was a "terrorist" group, but did not seem to include the Syrian wing, with whom the US is allied, playing a careful diplomatic game.
"PKK’s terrorist activities in Turkey, Iraq and Syria threaten the whole region," Davutoglu said, rejecting the US' official line.
Biden said Ankara had "taken very important steps" to step up security at its border, referring to the 90-kilometre stretch of land Islamic State still controls in northern Syria along Turkey's frontier.
However, this week, US Defence Secretary Ashton Carter, speaking in Davos on Saturday, said that the border was still “porous to foreign fighters” and that "the Turks can do more to fight ISIL,” an acronym used to describe Islamic State.
With regards to the PKK, Davutoglu reiterated that the group must give up its arms and leave the country or else operations against militants would continue, potentially furthering complicating efforts against Islamic State.
The Turkish army says it has killed around 700 PKK militants in the past six weeks, though this information cannot be independently confirmed.