After Saturday's aerial onslaught, Turkey is set to add ground forces to its new assault on Kurdish fighters over the border in northern Syria.
Ankara considers the US-backed YPG militia to be an extension of the outlawed Kurdistan Workers Party (PKK), which has long waged an insurgency in southest Turkey.
The strikes in Afrin province, which the YPG says have killed at least six civilians. could worsen strains with Washington.
US plans to set up a 'border force' inside Syria to protect territory held by its mainly Kurdish allies have outraged NATO ally Turkey.
Turkish Prime Minister Binali Yildirim said that: "Apart from Turkish armed forces, there are components of the Free Syrian Army participating."
Free Syrian Army rebels have travelled to the Turkish-Syrian border in armed pick-up trucks for the operation dubbed 'Olive Branch' by Ankara.
The Syrian government, which has threatened to shoot down Turkish planes, condemned the strikes, which it branded "brutal Turkish aggression".
On Sunday morning, four rockets fired from Syria hit the Turkish southern border town of Kilis, damaging houses, Turkey's state-run Anadolu Agency said, adding that there were no casualties.
Turkish security forces retaliated in kind, it said.