According to Anadolu Agency, the US military carried out reconnaissance operations in the Syrian Tel-Abyad area on the Syrian-Turkish border prior to the deployment.
Previously, the US-led coalition reportedly announced that it would establish a 30,000-strong border security force controlled by the Syrian Democratic Forces, led by with People's Protection Units (YPG) in Syria, which has already triggered Turkey's criticism. However, US Secretary of State Rex Tillerson later claimed that the United States was not creating a border security force, saying that the issue was "misportrayed."
Turkey has been threatening to launch an operation in Afrin against the Syrian Kurdish fighters since last week, after the US announced its decision to start training a border protection force. On January 19, the operation has de facto started with cross-shelling, however, according to Turkish Defense Minister Nurettin Canikli, no troops have been deployed in the city.
The minister added that the operation was "right to self-defense in line with international law," saying that the country was conducting necessary preparations for the upcoming operation aimed at eliminating all "terrorist corridors."