1224 GMT February 19, 2020
President Recep Tayyip Erdogan vowed that Ankara would emerge victorious from the campaign, AFP reported.
Turkey on Saturday launched operation "Olive Branch" aimed at rooting out the Kurdish People's Protection Units (YPG) militia, which Ankara sees as a terror group, from its Afrin enclave in northern Syria.
US Defense Secretary Jim Mattis called for Turkey to show "restraint", warning the offensive "disrupts what was a relatively stable area in Syria.
Turkish artillery on Tuesday pounded targets of the YPG inside Syria, the state-run Anadolu news agency said. Meanwhile, Turkish drones were also carrying out attacks, state television said.
The Britain-based Syrian Observatory for Human Rights monitor said "fierce clashes" were continuing especially north and southwest of Afrin.
As well as the artillery and air strikes, Turkish ground troops and Ankara-backed Syrian militants have punched over the border several kilometers (miles) into Syrian territory, taking several villages, according to state media.
After intense exchanges, Turkey's forces took control of the hill of Barsaya, a key strategic point in the Afrin region.
The observatory said 25 Ankara-backed militants and 26 Kurdish fighters had been killed in the fighting so far. It has also said 24 civilians have been killed on the Syrian side but this is vehemently rejected by Turkey which says it is only targeting militants.
Two Turkish soldiers have so far been killed in the offensive.
The campaign – which Erdogan has made clear has no fixed timetable – is fraught with risks for Turkey.
Two civilians have been killed inside Turkey in border towns in the last two days by rocket fire from Syria blamed on the YPG.
In Afrin, residents queued at bakeries and cars were on the streets as residents braced themselves for any violence.
The offensive against the YPG is also fraught with diplomatic sensitivities with Western capitals particularly concerned that it will take the focus away from eliminating Daesh.
France and the European Union have made similar comments to those made by Mattis.
But Ankara has expressed impatience with such sentiments, arguing that the YPG is the Syrian offshoot of the Kurdistan Workers' Party (PKK) which has waged a bloody three-decade insurgency against the Turkish state.
Turkey also launched airstrikes in northern Iraq on Kurdish militants planning an attack, the army said on Tuesday. Such raids have been frequent since a cease-fire with the PKK collapsed in 2015.
The UN Security Council discussed Turkey's intensifying offensive and the worsening humanitarian crisis in Syria on Monday but did not condemn or demand an end to the Turkish operation.