Mohammed Alloush was chief negotiator of the Riyadh-based High Negotiations Committee (HNC) and a member of Saudi-backed rebel group Jaish al-Islam (Army of Islam).
He cited many reasons for his departure, from shelling by forces loyal to President Bashar al-Assad to humanitarian emergencies and a perceived lack of will among international players.
“The international community is responsible for the stalemate of the negotiations,” Alloush said in a statement.
“It has refused to put pressure on the [Assad] regime or on the Russians, who have made no meaningful gestures to reaching a political solution. The negotiations have no meaning, and will have no positive result, if they only respond to the wishes of one side.”
His departure marks a faltering end to three rounds of peace negotiations that began in February, when the Assad government and the HNC agreed on a “cessation of hostilities” deal.
But numerous violations of the deal prompted the HNC to walk out of the talks in April, vowing it would only return if the situation on the ground evolved.
The UN special envoy for Syria, Staffan de Mistura, said last week talks would not resume for at least three weeks, and on Monday his office would not comment on what effect Alloush’s departure would have.
“It’s an internal HNC matter, so we can’t comment on the decisions they are making internally,” said de Mistura’s spokesperson, Josephine Guerrero. “We’re looking forward to continuing our work with all sides to make sure that our talks continue.”
Complicating matters last week, though, was the collapse of a proposal of the International Syria Support Group – a meeting of 20 countries including Russia and the United States – to begin airdrops of humanitarian aid in June.
The UN initially endorsed the deal, but it appeared to fall apart on Thursday when de Mistura indicated it would not go ahead without the Assad government’s cooperation.
But if the failed airdrop deal was the last nail in the coffin for the HNC’s participation in diplomatic efforts to end the five-year Syria conflict, it is also possible the rebels have been considering how to bolster military efforts, namely with the support of its hosts in Riyadh.
“I think what Alloush is signalling is: we’re not going to get what we want through negotiations, we’re going to have to do it through the battlefield,” says Scott Lucas, professor of international relations at the University of Birmingham in the UK.
“There are two ways of reading this. One is that he’s got the assurance from the Saudis that [they] are going to defy the US and start giving some significant support to the leading rebel factions,” Lucas suggests. “Alternatively, Alloush is putting the ball into the Saudi court and saying: if you really want to deal with Assad, you have to recognize you can’t count on the Americans, you can’t count on the Russians, you can’t count on the UN.”
Alloush is not the only prominent member of the HNC to denounce the UN process recently.
HNC leader Asaad al-Zoabi, who began advising rebel groups after defecting from the Syrian air force in 2012, has also suggested he wants to step down from his post, although has not confirmed any plans to leave for the time being.