BEIRUT (AP) - Within 24 hours of an interim deal aimed at reining in Iran's nuclear program, world powers raised hopes Monday for the first face-to-face talks to end the Syrian civil war as the United Nations called the warring parties to the table.
But huge gaps remain. The opposition remains vague on whether it will even attend the Geneva conference called for Jan. 22, and both sides hold fundamentally different visions on the very basics, particularly the future role of President Bashar Assad.
Nevertheless, Monday's announcement of a date for the talks after months of delay produced palpable hope that the precedent of successful nuclear negotiations with Iran might open new diplomatic channels that could help broker an end to the nearly 3-year-old civil war in Syria that has killed more than 100,000 people.
The nuclear deal between Tehran and world powers was announced in Geneva on Sunday. Success in negotiations on a final accord could pave the way for normalization of ties between Iran and the West, reshaping the Mideast political map.
As Assad's staunchest ally, Iran has given him significant financial support and is believed to have sent military advisers, trained pro-government militiamen and directed one of its proxies, Lebanon's Shiite Muslim Hezbollah, to fight alongside Assad's troops.
U.N. spokesman Martin Nesirky played down the possibility that the negotiations with Iran played a direct role in the movement on Syria, which followed a meeting in Geneva of senior diplomats from the U.S., Russia and the U.N.
The two tracks "are very separate, both tracks have been going on in different formats, in different locations," he told reporters. "So I would simply say that it was a good weekend for diplomacy."
Still, a senior member in the main, Western-backed Syrian opposition coalition expressed hope the nuclear deal would transform Iran into a "positive regional player," relinquishing its support for Assad.
"We hope the Iranian nuclear deal will provide impetus for a Syria deal," Abdelbaset Sieda of the Syrian National Coalition told The Associated Press. "The Iranian government must cut relations with the regime and leave the choice to the Syrian people."
A break between Iran and Assad is unlikely in the short term given the foothold the alliance gives Tehran in the Arab world. Still, a thaw between Iran and the U.S. - which backs the opposition coalition - could prompt Tehran to encourage Assad to make concessions, at least enough to keep talks going.
"If the Iran talks had not worked or if the Iranian deal had not come about yesterday, I think it might have been more hard-going today," said Salman Shaikh, director of the Brookings Doha Center. "In terms of the diplomatic atmosphere, there's certainly a feeling of some impetus."
The conference aims to work out a roadmap for Syria adopted by the U.S., Russia and other major powers in June 2012 - including creating a transitional government leading to the holding of elections.
Enormous challenges lie ahead. Even participation by both sides is by no means guaranteed.
Under pressure from the U.S., the Syrian National Coalition has dropped conditions that Assad step down before any talks and has eased demands for guarantees ahead of time that he will not be part of any transitional government - demands that the Syrian government has roundly rejected.
But the coalition is sticking to its condition that Assad release detainees and allow humanitarian corridors to provide access for desperately needed aid to rebel-held areas.
"These are trust-building measures that need to take place ahead of any talks, otherwise all efforts to convene a peace conference are futile," Sieda said.
Previous attempts to bring Syria's warring sides together have failed miserably, mainly because of disputes over who should represent the opposition and the government, as well as whether Iran, Saudi Arabia and other regional powers should be at the table, and - above all - whether Assad will remain in office in the future.
Syrian officials say Assad, whose troops currently hold momentum on the ground in Syria, will not surrender power and may even run again in elections due in mid-2014. The opposition says Assad cannot be part of any transition.
The Syrian government, in its first comment Monday, said it is ready to take part in a peace conference, while insisting it has a "constitutional duty" to protect the Syrian people from the "crimes of armed terrorist groups," a reference to the rebels.
"No one should underestimate the difficulties ahead," U.S. Secretary of State John Kerry said in a statement Monday. He called the meeting the best opportunity to "form a new transitional governing body through mutual consent."
White House spokesman Josh Earnest said Monday that removing Assad is the goal of the talks.
Nesirky suggested that the world powers were confident all sides would attend, saying the U.S., Russia and the U.N would not have announced the date "without consultations beyond that trilateral group."
In a further complication, even if the Syrian National Coalition represents the opposition at the table, it has limited control over the myriad rebel groups fighting Assad's forces, including dozens of Islamic brigades and al-Qaida-linked groups who say they won't put down their weapons until Assad steps down.
"The Geneva conference is an American-Iranian game that aims to boost Iran's reach in the region," said Mahmoud Allouche, a rebel spokesman in central Syria, echoing the sentiment of many fighters who mistrust the coalition and are suspicious the Iran nuclear deal would indirectly strengthen Assad's hand.
Louay Safi, a senior coalition member, said the opposition has received "promises" from the Americans and "indications" from the Russians that they will do "whatever they can" to get the government to open humanitarian corridors and release detainees.
"If the (Syrian) regime is going to defy both of them, then I don't think we have anything to talk about," he said.
The U.N.-Arab League's top envoy to Syria, Lakhdar Brahimi, said the creation of the transitional government "will be one of the most important elements that will have to be agreed upon during the conference."