Washington's top diplomat said on Friday that 24 hours into a planned five-day pause in fighting between Turkish and Kurdish forces in northern Syria the situation was improving.
Secretary of State Mike Pompeo, talking to reporters after meetings at NATO headquarters in Brussels said: "There was some activity today, but we also saw some very positive activity."
Scattered fighting was ongoing in northern Syria as Pompeo spoke, but he said that his understanding was that the 120-hour ceasefire began when the US-brokered ceasefire was announced on Thursday.
This means the 12-hour truce to allow Kurdish YPG fighters to perform a coordinated withdrawal from a 32-kilometre (20-mile) wide strip along the Kurdish border would run until Tuesday night.
"And we're hopeful in the hours ahead that both the Turks who were part of the agreement alongside of us as well as the YPG fighters in the region will take seriously the commitments they made," he said.
Turkish president Recep Tayyip Erdogan has warned that he will restart the operation to seize the border strip next week after the US-brokered pause ends in the YPG militia does not fully withdraw.
But Kurdish officials accuse Turkey of violating the ceasefire and a war monitor group has said that 14 civilians have been killed by Turkish air strikes and mortar fire since it was declared.