The UN restarted Syrian peace talks Monday to draw up a political transition roadmap in the coming weeks, but comments by the government and opposition exposed their fundamentally different visions for the future of President Bashar al-Assad.
Radical Islamist opposition negotiator Mohammed Aloush rejected the Syrian government's suggestion that the talks could eventually lead to a new government that would include the opposition, but would also keep al-Assad in power.
"Bashar must be put on trial and executed for his crimes against the Syrian people," said Aloush, who represents the Jaish al-Islam rebel group.
Despite deep differences between the two sides, there was no alternative to talks, UN mediator Staffan de Mistura told reporters.
"As far as I know the only plan B available is return to war - and to even worse war than we had so far," the UN envoy said.
"This is a moment of truth," he added.
The regime's chief negotiator, Bashar al-Jaafari, told reporters he had submitted a document to de Mistura, titled Basic Elements of a Political Solution, and pointed to "the force that we have from our people to represent our people in the Syrian talks."
Syrian Foreign Minister Walid al-Moallem had rebuked de Mistura on Saturday for saying that a presidential election was expected in 18 months. Al-Moallem said this was for Syrians to decide.
The opposition delegation likewise claimed that it represents the will of the Syrian people.
"For them, Assad being in power again is not acceptable," opposition spokesman Salim el-Muslet told Qatari broadcaster Al Jazeera in Geneva, without going as far as Jaish al-Islam's Aloush.
De Mistura said his efforts were based on the UN Security Council resolution from December 18. In that unanimous decision, the council said it supported free and fair elections to be held within 18 months.
Al-Assad's government has already set parliamentary polls for April 13, at a time when the UN-brokered talks on a political transition plan will still be ongoing, according to the UN schedule.
De Mistura said the current round was set to end around March 24, followed by a break of up to 10 days.
After that, he envisages a second round of talks lasting at least two weeks, another recess, and then a third round that should result in a substantive roadmap for political transition.
De Mistura is holding separate talks with the two sides on alternate days this week, rather than bringing them together.
If there was no progress in the coming weeks, de Mistura said, he would again ask the United States, Russia and the UN Security Council to intervene.
Washington has been supporting the armed opposition, while Moscow is one of al-Assad's few allies.
A partial ceasefire, brokered by these two world powers, went into effect on February 27 and has been holding since, despite some breaches.
The truce excludes the Islamic State terrorist militia and al-Qaeda's Syria branch, the al-Nusra Front, meaning their forces can be targeted.
The UN and aid groups have been using the cessation of hostilities to bring aid to besieged civilians.
But UN aid agencies and non-government humanitarian groups said in Geneva that there were hundreds of thousands of Syrians that they have yet to reach, especially in northern Homs and Aleppo.
"We use our collective voice to call on all parties, local and international, for this anniversary to be the last one and for the political talks to bring real peace and an end to the suffering in Syria," they said in a statement.