DUSHANBE, March 14, 2016, Asia-Plus -- The UN envoy to Syria, Staffan de Mistura, has described fresh peace talks in Geneva as a “moment of truth.”

The BBC reports that speaking before the negotiations, Mr de Mistura said on March 14 that “the mother of all issues” is political transition and the only alternative is a return to war.

But neither Syria''s government nor the opposition appear ready to compromise over the future of President Assad.

Diplomats are hoping to build on the fragile and partial truce, which came into effect at the end of February.

The UN-led talks represent the first serious diplomatic intervention since Russia began air strikes in September.

Syrian Foreign Minister Walid Muallem on Saturday ruled out any discussion on the future of President Assad.

But the main Syrian opposition alliance says Mr. Assad has to go.

US Secretary of State John Kerry responded by accusing Damascus of “trying to disrupt the process.”

Meanwhile, AFP reports that the UN mediator said on March 9 that a new round of talks aimed at ending the war in Syria will begin in Geneva on March 14 and will last no longer than 10 days.  “The negotiations would last not beyond March 24, when there would be a break,” Staffan de Mistura noted.

The truce between President Bashar al-Assad''s government and non-jihadist rebels is part of the biggest diplomatic effort yet to resolve Syria''s conflict, which has killed more than 270,000 people and displaced millions.

The partial truce, which was negotiated by Washington and Moscow and which does not apply to the Islamic State group or the Al-Qaeda-affiliated Al-Nusra Front, has largely held since it began on February 27.

As in the previous round, the negotiations have taken the form of “proximity talks” with de Mistura shuttling between the different sides.

In the past four weeks, 536 trucks had reportedly reached 238,845 people -- 150,000 of them in besieged areas, de Mistura said on March 9.

His special adviser Jan Egeland meanwhile hailed the fact that 10 out of 18 besieged areas had been reached, some with multiple convoys.

"The bad news is that we still have not reached six important besieged areas," Egeland said, referring to areas such as Daraya, Douma, besieged by government forces, and Deir Ezzor where some 200,000 people are under siege by IS jihadists.

The aim is to reach a total of 870,000 people in hard-to-reach areas by the end of April, el Hillo said.