Delegations from Syria's government, opposition and civil society are meeting in Geneva for the latest round of talks toward revising the war-battered country's constitution. The U.N. envoy for Syria, Geir Pedersen, was hosting the various sides Monday a day after saying Swiss health officials signed off on hygiene measures in place to help prevent the spread of the coronavirus. Several cases cropped up among the Syrian envoys during a previous round of talks. Nearly a decade into Syria's war, Pedersen acknowledged Sunday ``challenges'' in moving forward talks on the constitution, which notably do not include extremist factions that control some parts of Syria -- notably much of northwestern Idlib province. He said overcoming ``deep mistrust'' would take a long time, but hoped that work toward possible exchanges of detainees and the establishment of common ``principles'' in the discussions could help to overcome it. ``I hope that what we have achieved is actually the beginning of starting to build trust between the parties and that this building of trust could then be a door opener to a broader political process,'' he told reporters on Sunday. The meeting, involving 15 people from each delegation, is the fourth among the so-called Constitutional Committee. Another meeting is planned for January.