Turkey’s Prime Minister Binali Yildrim announced on 20 January that Turkish ground troops had crossed the border into northern Syria in its fight against Kurdish YPG militia.

Yildrim said the aim of the operation was to establish a 30km “safe zone” in the Kurdish-controlled Afrin enclave in Northern Syria. The Kurdish YPG responded by saying it had repelled Turkish troops in the Syrian city of Afrin.

Turkey’s encroachment into Syria risks increasing tensions with the US, which recently announced it would train an army to patrol Syria’s borders, in which the YPG would play a key role. The US has backed the YPG in the battle against the Islamic State of Iraq and Syria (Isis).

Turkey intervened in the Syrian civil war in August 2016, when it sought to limit the expansion of Kurdish militia west of the Euphrates river and drive Isis from key strategic border areas.