The latest attacks in opposition-held northwest Syria marks "one of the most alarming moments" in the nearly 9-year-old conflict, UN Secretary-General Antonio Guterres said on Friday.
"The most pressing need is an immediate ceasefire before the situation gets entirely out of control," he said. "In all my contacts with those involved, I have had one simple message: step back from the edge of further escalation."
The UN chief's plea follows reports that at least 11 Syrian soldiers were killed on Friday by strikes from Turkish drones in the northwestern province of Idlib.
"I also reiterate my appeal for civilian protection," he told reporters at a brief news conference outside Security Council chambers.
"Fighting has brought nothing but ruin and misery," Guterres said. "There is no military solution. The only path is a UN-facilitated political process."
Asked if the world organization should dispatch UN personnel to get a clear picture of what is happening, he said. "There is preparation for a humanitarian mission exactly with that purpose."
The secretary-general said nearly 1 million people have fled their homes in the past three months as airstrikes continue to hit schools and medical facilities.
"Even camps and other sites where displaced families have sought shelter have been struck by shelling," he said. "The noose keeps tightening, as the frontlines are moving into more densely populated areas."
The civilian population under threat in Syria's northwest has been put by the United Nations at 3 million.