BEIRUT/GENEVA — The United Nations has adopted a cautious approach to the Syria talks it launched this week, avoiding raising expectations that this latest initiative can end a four-year-old conflict which has so far defied all diplomatic efforts to resolve it. UN Syria envoy Staffan de Mistura says he wants to talk to diplomats, activists and political and military leaders to see if there is any new common ground since a roadmap for ending the war was declared in 2012. Diplomats are skeptical his efforts will come to anything, but agree this year alone much has changed, both on the battlefield and in the relationships between allies and opponents of Syrian President Bashar Al-Assad. "The balance of power has shifted," said one Western diplomat who tracks Syria. "The government sees that they have lost some battles but not the war. But it could still be the beginning of the end, everything is possible." On the battlefield Sunni insurgents including Al-Qaeda wing Nusra Front have made significant gains in recent weeks in the northwestern province of Idlib, edging closer to the government-held heartland of Latakia. In the southwest rebels have captured a crossing with Jordan, suggesting new resolve by Arab backers who want Assad to step down. But diplomats say Assad's inner circle remains strong after government defections earlier in the uprising and main allies Iran and Russia are steadfast. Hardliners including Daesh (so-called IS) have advanced at the expense of more mainstream rebels since the last round of Geneva talks in February 2014. US-led forces have been striking the group in Iraq and in Syria since the summer. De Mistura, whose two predecessors resigned in frustration at the failure to make headway, has already had to drop his first initiative — a proposed freeze to hostilities in the city of Aleppo which he hoped could expand into a wider truce. He is not calling his consultations "peace talks" or "Geneva 3", a name that suggests a third attempt at a UN-brokered truce. But some diplomats think that is what his separate, one-on-one discussions are designed to lead into. Participants invited include the Syrian government, a myriad of opposition groups and non-jihadist armed factions, civil society members, non-governmental organizations, representatives of five major world powers, Iran and bordering countries. The most fertile ground for consensus may be widespread opposition to Daesh, a common foe which has surged through Iraq and Syria. — Reuters