The US president later tweeted: "In case the Kurds or Turkey lose control, the United States has already taken the 2 ISIS militants tied to beheadings in Syria, known as the Beetles, out of that country and into a secure location controlled by the US".
President Erdogan wants a buffer zone to which he can send back some of the 3.6 million Syrian refugees his country hosts.
A U.S. soldier sits atop an armoured vehicle during a demonstration by Syrian Kurds against Turkish threats next to a base for the US-led worldwide coalition on the outskirts of Ras al-Ain town in Syria's Hasakeh province near the Turkish border on October 6, 2019.
I do so in protest of the Turkish armed forces' invasion of Northern Syria. Some made victory signs, shouting "Allahu akbar" (God is greatest) and waving Syrian rebel flags as they advanced toward Ras al Ain.
USA -backed, that is, until President Donald Trump announced a sudden withdrawal of forces in northeastern Syria Monday, sparking chaos in the region.
The United States will introduce sanctions against Turkey if it acts in a way that is disproportionate and inhumane, said a US State Department official.
Kotey, who has a Ghanaian father and a Cypriot mother, was captured along with Elsheikh by Syrian Democratic Forces (SDF).
SDF forces had recovered a hamlet early in the morning, he said.
Doctors Without Borders (MSF) said in a statement that it had to close down the hospital it supported in Tal Abyad.
In a meeting Friday with reporters, Sedar Kilic, the Turkish ambassador to the United States, said that his government had no intention of "slaughtering" Kurdish fighters, as some U.S. lawmakers have alleged, but that it was determined to bring an end to Kurdish occupation of the border area and would not stop until it had reached its goals.
The International Rescue Committee aid group said 64,000 people in Syria have fled since the campaign began. The towns of Ras al-Ayn and Darbasiya have become largely deserted.
Erdogan also said that some 370,000 refugees have returned to the northwestern Syrian cities of Afrin and Jarablus.
Turkey also says one of its soldiers was "martyred". It says it has killed hundreds of fighters since Wednesday.
Overnight, clashes erupted at different points along the border from Ain Diwar at the Iraqi frontier to Kobani, more than 400 km to the west.
Turkish and SDF forces exchanged shelling in Qamishli among other places, the SDF's Qamishlo said.
Corabatir, who is the president of the Research Center on Asylum and Migration and is a former spokesman in Turkey for the United Nations refugee agency UNHCR, said forced deportations are against worldwide laws and Turkey's open-border policy.
Fighting broke out in several locations along the roughly 120-kilometre wide front where operations are focused, the Syrian Observatory for Human Rights and a Kurdish military official said Thursday.
The SDF said Turkish air strikes and shelling had killed nine civilians.
The Syrian National Army, a group of rebel factions backed by Turkey, said it had seized a dozen villages in northeastern Syria as part of the ground offensive.
People help a wounded boy as they take cover after mortars were fired from Syria in Akcakale, Turkey, on Thursday. Authorities there said a vehicle bomb had blown up in the city, killing three civilians and wounding nine.
The SDF now holds most of the territory that once made up Islamic State's "caliphate" in Syria, and has been keeping thousands of fighters from the terrorists group in jail and tens of thousands of their family members in camps. He was happy about the Turkish offensive, he said. "Unfortunately in any conflict zone, some doctors and medical employees have to leave, leaving very few resources to care for those people".
"Discussion is underway with the relevant bodies and organisations to find a solution or alternative location to move the camp to", it said.
A USA official, speaking on condition of anonymity to brief reporters, said the patrol was not in support of operations against the Turkish offensive.
Trump told reporters Wednesday that he learned the Kurdish didn't fight alongside the U.S.in the 1940s in a "very, very powerful article".
Trump later added, "We are going to possibly do something very, very tough with respect to sanctions and other financial things", with regard to Turkey.
It comes as Donald Trump said he hopes he can mediate between Turkey and the Kurds following Turkey's offensive on US-allied Kurds in northeast Syria.
In the face of widespread global criticism for his military foray into northern Syria, President Recep Tayyip Erdogan remains defiant, standing by his pledge to return as many refugees as possible to a border corridor that will be carved out by force.
"Quashing criticism of Turkey's military operations and targeting journalists and social media users with threats of detention and criminal prosecutions is unacceptable".
Turkey's President Tayyip Erdogan criticised Europe for failing to support the Turkish offensive and threatened to send refugees to Europe if the European Union did not back him.