RIYADH - Syrian opposition groups met for a second day in the Saudi capital Thursday seeking unity on a transition plan for their war-torn country despite differences over the future of President Bashar al-Assad.

Some 100 delegates began meeting on Wednesday under tight security at a luxury hotel in Riyadh, the first time a broad range of both political and armed factions from the Syrian opposition have sat at the same table.

The talks follow a major diplomatic push to resolve Syria’s nearly five-year civil war, with top diplomats from 17 countries - including backers and opponents of Assad - agreeing in Vienna last month on a transition plan.

It would see a transition government set up within six months and elections held within 18 months, and calls for negotiations between the opposition and Assad’s regime by January 1. US Secretary of State John Kerry said the meeting had made progress, boosting the chances that peace talks could take place.

“It’s not locked in yet, but the meeting in Saudi Arabia appears to be very constructive at this point, and we need to wait for the results of that conference,” Kerry told reporters on the sidelines of the UN climate summit in Paris. “But I think everybody is moving in the direction that they want to rapidly try to get to a political process and get it underway under UN auspices,” he added.

Meanwhile, the first batch of German troops and aircraft took off Thursday for Turkey as part of a deployment in the battle against the Islamic State group in Syria. Forty soldiers and two Tornado reconnaissance jets left from the Jagel military airbase in northern Germany’s Schleswig-Holstein state.

An A310 MRT aerial refuelling jet left separately from Cologne-Wahn base for the Incirlik airbase in southern Turkey. The Riyadh talks aim to form a unified bloc for the potential talks and opposition sources said some progress had been made on the first day.

A source in the National Coalition, the main opposition group which is based in Istanbul, said delegates had agreed on a set of basic principles, including ensuring Syria is a “pluralist and civil state” and guaranteeing the country’s territorial integrity. The source, whose information was confirmed by a second opposition figure, said delegates also agreed on “the preservation of state structures, the restructuring of military and security bodies, and the rejection of terrorism and the presence of foreign combatants”. Opposition figures also agreed to create a body of 23 to 31 members to supervise a negotiating team, another source said.

Few details were emerging from the talks but there were no signs of agreement yet on one of the most contentious issues, the fate of Assad. Western- and Arab-backed rebel groups insist the Syrian leader must step down immediately but internal opposition groups disagree, as do Assad’s key backers Tehran and Moscow.

Some delegates have nonetheless expressed hope the end result of the talks will be positive, with questions on Assad’s future potentially put off until later. National Coalition chief Khaled Khoja said Wednesday he expected the meeting to agree on “forming a negotiating team and on the principles of negotiations” with Assad’s regime. Not all of Syria’s armed factions are attending the talks, with militants such as the Islamic State group and the Al-Qaeda affiliated Al-Nusra Front excluded.

Meanwhile, the Islamic State militant group on Thursday recaptured two areas in central Syria from government forces, just weeks after losing them, a monitor said. “Syrian army units withdrew from all of the Maheen and Hawareen areas after an IS attack,” said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

Riyadh has been among those calling most strongly for Assad’s departure and on Thursday Saudi Foreign Minister Adel al-Jubeir insisted he must leave. “Bashar al-Assad has two choices: leave through negotiations, which would be fastest and easiest, or he will be removed by force, because the Syrian people refuse for this man to be allowed to stay in power,” Jubeir said.

Jubeir’s comments came as leaders from the six-nation Gulf Cooperation Council held their annual summit in Riyadh.

In a declaration after the talks, the Gulf monarchs said they “support a political settlement... that guarantees the territorial integrity and independence of Syria.”

The United States will hold further discussions on Syria with Russia and the United Nations in Geneva on Friday.

The next meeting between top diplomats in the Vienna process is expected to take place later this month in New York.

Since erupting in mid-2011, the conflict in Syria has left more than 250,000 dead and forced millions from their homes.