The United Nations mediator in the Syrian peace talks says it is time for Syria's opposition to accept it has not won the six-and-a-half-year war against President Bashar al-Assad.
Special Envoy for Syria Steffan de Mistura says the war is almost over because many of the countries that got involved did so mainly to defeat IS.
With IS, or ISIL, now reeling and losing its footholds in the country, he says it is time for the opposition to, instead, "win the peace."
"That's why, when I say that that we are now at the moment of truth very soon, and where we hope that those countries who can influence the government to say, 'Now is the time to negotiate,' of course, the military situation has been improving, but it's time to negotiate, and for the opposition to do the same in a realistic, unified way. That is going to be very soon, after Raqqa and Deir al-Zor."
Asked if he is implying President Assad has won the war, Mr de Mistura says the pro-government forces have advanced militarily but nobody can claim to have won the war.
Estimates vary, but at least 330,000 people are believed to have died.
Mr de Mistura says victory can only come with what he calls a "sustainable political long-term solution."
He says, otherwise, lower-intensity guerilla conflicts could continue for the next decade and there might be no reconstruction.
His remarks come as the head of the UN Commission of Inquiry on Syria says government forces are continuing to deliberately target civilians.
Paulo Pinheiro says that includes using chemical weapons, and the United Nations is reporting it has now concluded government forces did so in April at Khan Sheikhoun.
"In several instances, government forces used chemical weapons against civilians in opposition-held areas, including Khan Sheikhoun, Idlib, on 4th April. We gathered excessive evidence, including 43 interviews with victims, eyewitnesses, first responders, medical staff and persons who visited the site, as well as photos of remnants and satellite imagery. On the basis of this information, we concluded that a chemical attack was carried out by a Syrian SU-22 aircraft, which dropped three conventional bombs and a sarin bomb in Khan Sheikhoun. This sarin attack killed over 80 individuals, most of them women and children, and injured hundreds of others."
But Mr Pinheiro has gone further, also criticising the United States-led coalition opposing the government forces for its own deadly air strikes.
"We continue to investigate additional allegations that the international coalition's air strikes carried out as part of the ongoing offensive to repel ISIL from al-Raqqa is resulting in an increasing number of civilian casualties."
Mr Pinheiro has referred to an incident earlier this year when US F-15 jets targeted a building adjacent to a mosque near Aleppo, killing at least 38 people.
US military officials had claimed they were targeting al-Qaeda members, saying it was legal and only one person died.
But Mr Pinheiro says US military investigators did not visit the site, nor interview surviving victims.
"Our latest report finds that the United States force failed to take all feasible precautions to protect civilians and civilian objects when attacking alleged terrorists and destroying part of a mosque complex in al-Jinah, Aleppo, on 16 March, resulting in an alarming loss of civilian lives, a serious violation of international humanitarian law."
The latest round of stalled peace talks on the Syrian crisis are due to get underway next month in Geneva.
The United Nations has helped broker multiple truces during the war, but none has proved lasting.
The main opposition grouping, the Saudi-backed High Negotiations Committee, still insists President Assad must leave office as part of any peace deal.
