The United States is willing to provide ammunition alongside humanitarian assistance to Turkey in Syria's Idlib region, the U.S. special representative for the region James Jeffrey said on Tuesday.

"Turkey is a NATO ally. Much of the military uses American equipment. We will make sure that equipment is ready and usable," Jeffrey told reporters.

Separately the U.S. Ambassador to Turkey, David Satterfield, said at the briefing that Washington is examining Ankara's request for air defense systems.

Turkey has requested Patriot missiles amid heightened military tension in Idlib.

Attacks by the forces of the Bashar Assad regime have killed 55 Turkish soldiers in the past month in Idlib. President Recep Tayyip Erdoğan has threatened to push back Assad forces if they do not pull back to predetermined lines.

Regime airstrikes targeting Turkish troops heightened tensions between pro-opposition Turkey, Assad and its ally Russia.

The latest crisis stems from a Russian-backed Assad regime military campaign to retake Idlib province, which is the last opposition-held stronghold in Syria. The offensive, which began Dec. 1, has triggered the largest single wave of displacement in Syria's nine-year war, sending nearly 950,000 people fleeing to areas near the Turkish border for safety.