The Syrian government and opposition open Monday indirect negotiations in Geneva to try to end five years of civil war, although differences remain abysmal.
Washington and Paris on Sunday called for negotiations "real" and accused the regime of trying to "derail the process" by refusing to discuss the future of President Bashar al-Assad, which the opposition calls the game.
In Geneva, the UN special envoy to Syria, Staffan de Mistura, said Monday that "political transition" will be decisive in the negotiations.
"What is the main issue? The mother of all issues is the political transition," he said in reference to the main issue of contention between the Syrian government and the opposition, which claims that President Bashar al-Assad leave power before installation of a "transitional body".
The Syrian conflict, which began on 15 March 2011 with a peaceful protests bloodily repressed, has become a complex struggle with a large number of local and international actors.
Since then, more than 270,000 people have died and millions have fled their homes, leading by extension a migration crisis in the European Union.
- Context different -
This new session starts in a radically different to the previous environment, in late January, when the UN even got ripped off talks.
A truce, sponsored by the United States and Russia, which entered into force on 27 February between the regime and the "moderate" rebels in Syria, remains despite some violations. This has allowed the UN to supply humanitarian aid to about 250,000 people stranded in embattled areas.
Europeans and Americans insisted on Sunday the need to respect the truce and humanitarian aid is delivered, to ensure that the negotiations are "credible".
"Any violation, even sporadic, the cessation of hostilities endangers the process," said US Secretary of State John Kerry.
Russia, whose military intervention in Syria has allowed the regime recuperrar ground to the rebels insisted on "the need" to include in peace negotiations the Kurds, so that there is no de facto partition of Syrian territory.
- Body transition -
For the first time, the Geneva negotiations will address the future of Syria specifically.
"We hope that negotiations begin tomorrow with talks on the transition body, which will have all powers, including the President of the Republic," said Al Meslet.
"In that body there will be no role for those who have committed crimes, including Bashar al Asad," he insisted the opposition representative.
However, the regime does not arise discuss the future of Al Asad, re-elected in 2014 during the war for seven years.
The regime also has a very different from what must be the transitional authority interpretation. For him, it will be a single cabinet reshuffle to form a "unity government", ie expanded opponents but under the authority of Bashar al-Assad.
That new government, according to Syrian Foreign Minister Walid Mouallem, appoint a committee to "draft a new constitution or amend the current". The text would then be submitted to a referendum.
Even if there is an agreement between the rebels and the regime in Geneva, the fighting would continue in Syria, as the jihadists Front Nosra, local branch of Al Qaeda and Islamic State control more than half the territory, and are excluded from the truce in force.