GENEVA — Ever get an invitation and think to yourself, “I wonder who else is going? Should I go?”

On Tuesday, an assortment of rival Syrian politicians and warlords got a similar invitation — for tea, coffee and talks in Geneva. It came from Staffan de Mistura, the United Nations envoy assigned to bring them together to consider ending the five-year-long war they have been waging on their own people.

Mr. de Mistura said details of the guest list were too “sensitive” to divulge. He let it be known that he does expect formal responses, and hopes the guests will show up in time for the start of the talks on Friday morning. This is Switzerland, after all.

With any peace talks, negotiations over how to hold negotiations are always delicate and intensely fought over, but this diplomatic dance is particularly odd. It is not only unclear who will come, but it is also unknown whether they are even close to ready to make the compromises necessary to reduce the suffering of Syrian civilians even slightly. Mr. de Mistura’s plan to keep people in separate rooms and shuttle among them is another indication of how complex the situation is.

The secrecy has also offered ample opportunity for propaganda by the various factions, some of whom quickly claimed to have been invited — or to have heard that their rivals had been invited.