Turkish President Recep Tayyip Erdogan on Monday threatened to launch a ground operation into Syria after cross-border air strikes on Kurdish positions and deadly fire on Turkey.
"There is no question that this operation be limited to only an aerial operation," Erdogan told reporters on a flight home from Qatar after attending the opening of the World Cup.
The Turkish leader has threatened a new military operation into northern Syria since May.
Overnight, Turkey hit dozens of targets in northern Syria as well as northern Iraq, a week after an Istanbul bomb attack killed six people and which Ankara blamed on the Kurdistan Workers' Party (PKK).
Kurdish groups and authorities have denied responsibility for the November 13 bombing, which also wounded 81 people, and which revived bitter memories of a wave of attacks in Turkey between 2015 and 2017.
Rocket fire from Syrian territory on Monday killed at least three people, including a child, in Turkey's border town of Karkamis, said interior minister Suleyman Soylu.
Soylu vowed a "strong response."
"Competent authorities, our defence ministry and chief of staff will together decide the level of force that should be used by our ground forces," Erdogan said.
"We have already warned that we will make those who violate our territory pay."
- Funerals -
Turkey's raids, mainly targeting positions held by Kurdish forces in northern and northeastern Syria, killed at least 35 people and wounded 70 others, according to the British-based monitoring group the Syrian Observatory for Human Rights (SOHR).
Ankara said the targeted Kurdish bases were being used to launch "terrorist" attacks on Turkish soil.
On Monday, thousands of people gathered to bury 11 people who died in Al-Malikiyah in Syria's far northeast, including a journalist working for a Kurdish news agency, with the caskets draped in red-white-and-green Kurdish flags.
"We urge the world, all those who care about human rights and the great powers" to press Turkey to stop its strikes that "target us with planes and drones", a mourner named Shaaban, 58, told AFP during the funerals.
In Berlin, the German foreign ministry urged Turkey to "react proportionally and to respect international law", adding that "civilians at all times must be protected".
SOHR said Kurdish fighters and Syrian soldiers bore the brunt of the casualties during the attacks in the areas of Raka and Hassake in the northeast and Aleppo in the north.
The Kurdish-led Syrian Democratic Forces (SDF), among those attacked, said Turkey launched new air strikes on Monday.
The strikes also targeted PKK bases in mountainous northern Iraq and bases of the Kurdish People's Protection Units (YPG) in Syria, the Turkish defence ministry said.
The PKK has waged a bloody insurgency for decades and is designated a terror group by Ankara and its Western allies.
- '70 planes and drones' -
Ankara considers the YPG to be a PKK-affiliated terror group.
Erdogan said "70 planes and drones" that "penetrated 140 kilometres (87 miles) into northern Iraq and 20 kilometres into northern Syria" carried out the the weekend strikes.
An SDF spokesperson told AFP that Turkish airplanes launched fresh strikes on Monday near Kobani. The SOHR confirmed the strikes. The SDF said a regime forces' position was hit.
On Monday, there was artillery exchange between Turkish forces backed by Syrian proxies and the SDF, according to an AFP correspondent.
Erdogan said he had had "no discussion" with either US President Joe Biden or Russian President Vladimir Putin "on the subject of the operation."
Turkey's latest military push could create problems for its complex relations with its Western allies -- particularly the United States, which has relied mostly on Syrian Kurdish militia forces in its fight against IS jihadists.
Turkey has often accused Washington of supplying Kurdish forces with weapons.
Russia for its part backs pro-Damascus militia in the region.
Between 2016 and 2019, Turkey launched three large-scale operations in northern Syria against Kurdish groups.