Turkish ground troops have crossed the border into northern Syria, its defence ministry has said.
"The Turkish Armed Forces and the Syrian National Army have launched the land operation into the east of the Euphrates river as part of the Operation Peace Spring," it said on Twitter.
It comes after Turkish President Recep Tayyip Erdogan announced Turkey had started its military operation into Syria.
The attack, in the north east of the country, will target both Syrian Kurdish as well as ISIS fighters.
Turkey's government shared pictures of its defence minister Hulusi Akar with other military officials as the ground offensive got under way on Wednesday.
President Erdogan said Turkey is reinforced by their Syrian rebel allies and that the offensive hopes to eliminate a "terror corridor" along the southern Turkish border.
He said the offensive, dubbed "Operation Peace Spring", would aim to eliminate threats from the Syrian Kurdish YPG militia and the Islamic State militants, and enable the return of Syrian refugees in Turkey after the formation of a "safe zone" in the area.
"Our mission is to prevent the creation of a terror corridor across our southern border, and to bring peace to the area," Mr Erdogan said on Twitter.
"We will preserve Syria's territorial integrity and liberate local communities from terrorists."
The move comes as Foreign Secretary Dominic Raab said he had "serious concerns" about Turkey's military action.
He said: "This risks destabilising the region, exacerbating humanitarian suffering, and undermining the progress made against Daesh which should be our collective focus.
"Turkey has shown considerable generosity in hosting so many Syrian refugees.
"But we will not support plans for returns until the conditions are in place for a voluntary and safe return home."
