ANKARA - Turkish ground troops entered Syria on Sunday to push an offensive against Kurdish militia as rocket fire hit a border town in apparent retaliation.
But the campaign risks further increasing tensions with Turkey 's NATO ally the United States -- which has supported the YPG in the fight against Islamic State jihadists -- and also needs at least the tacit support of Russia to succeed.
Prime Minister Binali Yildirim said troops crossed into the YPG-controlled region in Syria at 0805 GMT, the Dogan news agency reported.
Turkish artillery and war planes pounded YPG sites around Afrin and total of 153 targets, including YPG refuges and weapons stores have now been hit, according to the army.
The state-run Anadolu news agency said the Turkish troops, whose number was not specified, were advancing alongside forces from the pro-Ankara rebel Free Syrian Army (FSA) and were already five kilometres (three miles) inside Syria .
An AFP correspondent on the southwestern edge of the Afrin region saw a warplane bombing the western outskirts of the area early on Sunday.
A small unit from a Turkish-backed rebel group was manning a monitoring point on a hilltop overlooking several Kurdish-controlled villages below.
- 'No need to worry' -
The operation is Turkey 's second major incursion into Syria during the seven-year civil war after the August 2016-March 2017 Euphrates Shield campaign in an area to the east of Afrin against both the YPG and IS.
The army said IS was also being targeted in this operation although it no longer has any major presence in the Afrin area.
President Recep Tayyip Erdogan had repeatedly vowed that Turkey would root out the "nests of terror" in Syria of the YPG, which Ankara accuses of being the Syrian offshoot of the Kurdistan Workers' Party (PKK).