"We believe Russia has killed dozens of Turkish military personnel in Syria," U.S. Secretary of State Mike Pompeo told Reuters late Tuesday.
"The United States will consider additional help to Turkey," he added.
Turkey launched Operation Spring Shield on Feb. 27 after at least 34 Turkish soldiers were killed in an airstrike in Idlib province and after repeated violations of previous cease-fires.
Under a 2018 deal with Russia, the Turkish troops were in Idlib to protect civilians from attacks by the regime and terrorist groups.
Turkey and Russia, which back opposing sides in Syria's war, agreed on March 5 to halt military activity in the northwestern Idlib region after an escalation of violence displaced nearly a million people and brought the two sides close to confrontation.
The deal addresses Turkey's main concerns, stopping a flow of refugees and preventing the deaths of more Turkish soldiers on the ground.
