The Turkish military, along with forces from the Syrian National Army, have mounted Operation Peace Spring, an incursion into territory controlled by the Kurdish-led Syrian Democratic Forces.
Turkish President Recep Tayyip Erdogan has been threatening an incursion into Kurdish-controlled Syrian territory for months, asking the US to help Turkey create a "safe zone" there for Ankara to repatriate Syrian refugees who settled in Turkey during the eight-year Syrian civil war.
Turkey originally wanted to stage the invasion to create a buffer zone along its border against Kurdish forces, who control the northeastern part of Syria, as well as some land near Aleppo in the west. Turkey considers the Kurdish forces there terrorists.
The SDF was an essential partner force in the mission to destroy ISIS; on Sunday evening, Trump announced his intention to pull US forces out of northeastern Syria, which Kurds call Rojava, essentially giving a green light to a Turkish attack on the Kurds.
The first Turkish air strikes in northeastern Syria began Wednesday. The ground invasion began shortly thereafter.
Reuters, quoting Turkish media, reported that the ground incursion targeted four points in Rojava — two close to the Syrian town of Tal Abyad further west, and two near the town of Ras al-Ayn.
The Turkish Ministry of Defense said it had conducted 181 air strikes thus far and removed part of its border wall with Syria to allow ground troops in, according to The New York Times.
The Times reported that between 50 and 100 US troops pulled out of Rojava ahead of the operation. While Trump has said that the US will not be militarily assisting either side in the conflict, The Times also reported that until Monday, the US was assisting Turkey with intelligence that may have helped them target Kurds as late as Monday.
Turkish forces and their allied Syrian groups claimed to have captured at least two villages from SDF forces, The Guardian reports.
On Wednesday, The Times reported as many as eight casualties in the initial strikes. On Thursday that number rose to at least 16.
CNN reported 13 SDF fighters and three civilians killed; the Kurdish Red Crescent put the number of civilians at seven, including two children, according to the BBC.
NBC reported that four Christians had been killed, despite Trump's promise to protect religious minorities in the area.
Turkish officials reported that 109 Kurdish fighters had been killed, although that number appears to be inflated. The Syrian Observatory for Human Rights, a monitoring group based in the UK, reported 33 SDF wounded, according to The Times.
In what seems to be a response from Kurdish forces, Turkish towns near the border were shelled on Thursday, killing six, including an infant, and wounding 65.
As many as 12,000 ISIS prisoners have been held in makeshift prisons guarded by SDF forces in Syria.
But with the SDF turning its attention to the border clash with Turkey, SDF leaders have acknowledged the impossibility of guarding the prisons at the same time with so few resources.
Around 60,000 refugees have fled the area near the fighting, according to The Times.
The streets outside of Ras al-Ayn were choked with vehicles Wednesday, with families attempting to flee the area. A group of refugees told CNN's Clarissa Ward that they didn't know where to go or where they might find safety.
The displacement has sparked fears in neighboring Iraq, where the Foreign Ministry released a statement saying Operation Peace Spring could "directly impact security in Iraq," with refugees and militants streaming across the border.
Since Sunday, the world has expressed outrage over both Trump's decision to pull US forces and Erdogan's incursion into Syria.
Even Trump's Republican allies condemned his decision to move US troops away from Syria's border with Turkey, leaving Kurdish partners vulnerable to attack. Sen. Lindsey Graham, one of Trump's biggest supporters, said Trump's actions were a "disaster in the making."
Five members of the UN Security Council —France, the UK, Germany, Belgium, and Poland — requested that a meeting regarding the Turkish incursion be held Thursday, and Iran and Russia have both cautioned Turkey about the destabilizing nature of its actions.
Erdogan hit back against his European detractors, threatening to send millions of Syrian refugees to the continent, The Guardian reported.
