Turkish government outlets and the Syrian Defense Forces (SDF), the mostly Kurdish militias mainly responsible for defeating the Islamic State in that country, offered wildly differing death tolls on both sides on Friday following Ankara’s decision to invade Syria this week.

The government of Islamist President Recep Tayyip Erdogan invaded northern Syria this week in what it calls “Operation Peace Spring,” a plan to eradicate the Kurdish presence in Rojava (Syrian Kurdistan) and replace the Kurds with the four million Syrian refugees, most of whom are Arabs, who have fled to Turkey since the Syrian Civil War began in 2011. The invasion began shortly after Washington announced it would relocate the 50 troops present in the area to elsewhere in Syria, taking them out of the way of the Turkish military.

Turkey is a NATO ally, meaning the United States is bound by treaty to defend the country in case of an invasion. Article 5 of the NATO treaty has only been invoked once – by America in a call to send NATO troops to Afghanistan following the September 11, 2001, jihadist attacks.

The SDF is also allied with America, though as a non-state actor, Washington has no responsibility by treaty to defend the group. Most of its members belong to the People’s Protection Units (YPG/YPJ), Rojava’s Kurdish army. The SDF eliminated the Islamic State’s presence in Raqqa, the jihadist group’s “capital,” and is currently holding thousands of jihadists prisoner in territories that Turkey has begun to attack.

Turkey considers the SDF indistinguishable from the Kurdistan Workers’ Party (PKK), a U.S.-designated Marxist terrorist organization active in Turkey.

In a press statement Thursday, the SDF claimed that it had “frustrated” Turkey’s attempts at taking over Kurdish towns.

“Syrian Democratic Forces confronted a field incursion attempt by the Turkish occupation army in the hub of Tal Halaf and Sluk city,” the group said, adding that Islamic State elements appeared to take advantage of the chaos to attack Kurdish soldiers.

Firat News Agency, an Amsterdam-based outlet that the BBC has described as “pro-PKK,” published details of a press release on Friday from the SDF that claimed the Kurds had killed hundreds more Turkish soldiers “and terrorists” – meaning members of the Free Syrian Army (FSA) – than the 16 SDF fighters allegedly killed in battle since “Peace Spring” began.

“As a result of the clashes on the two mentioned dates, 16 of our heroic comrades were martyred,” the SDF said. “As a result of the clashes during the mentioned dates, 262 Turkish-backed jihadists were killed.”

The press release also says “many” civilians were killed in Turkey’s assault, which reportedly featured air attacks as well as tanks rolling into SDF territory.

Anadolu Agency, the official news agency of the government of Turkey, placed the number of “neutralized” SDF forces, or “terrorists,” at far higher than 16. The Turkish government uses the word “neutralize” to include all fighters removed from the battlefield, either killed or taken prisoner. Anadolu did not identify how many of the “neutralized” were still alive.

“A total of 342 terrorists have been ‘neutralized’ since the start of Operation Peace Spring in northern Syria, Turkey’s defense minister said on Friday,” Anadolu reported. “Hulusi Akar’s comments came after his meeting with top military officials in Turkey’s capital Ankara, where he said ‘every kind of measures have been taken’ in operation areas.”

Akar called the operation “successful” so far despite SDF reports that the Turkish military had been “frustrated.”

The last time Turkey attempted to invade Syria, in 2018’s “Operation Olive Branch,” the YPG put up a much more formidable fight than the Turks had prepared for and, at one point, declared victory. Turkey captured the city of Afrin in Rojava in March as the YPG avoided further fighting in the service of preventing a massacre. By September, rumblings of a Kurdish challenge in Afrin began to resurface.

The battled-hardened YPG, on the heels of defeating the Islamic State, moved a significant challenge to Turkey despite not having its advanced weaponry or an air force. Erdogan purged his most capable military leaders and thousands in the rank and file, following a failed coup attempt he suffered in 2016, leaving the Turkish military significantly weakened.

The Turkish army appears to be relying heavily on air support for “Operation Peace Spring,” but it is also driving armored vehicles into captured towns. On Friday, the Agence France-Presse (AFP) reported seeing “dozens” of Turkish army vehicles crossing the border into Syria and cited the Syrian Observatory for Human Rights (SOHR), an NGO operating in the country, as having evidence of Turkish soldiers capturing 11 villages.

The Kurdistan Regional Government (KRG) of Iraq, which has long had icy relations with the PKK and YPG, issued a statement following the launch of the operation Tuesday, urging Turkey, with whom it has maintained friendly ties, to stop its invasion.

“The government calls on Turkey, as a member of the Global Coalition, to avoid any initiative that would undermine the progress made against ISIS, including jeopardizing the secure detention of terrorist fighters,” the KRG said, according to the Kurdish outlet Rudaw. “The consequences of military escalation have implications far beyond Syria’s borders, creating the conditions for a return of ISIS and a mass displacement of people.”

The KRG’s fighters, the Peshmerga, have also waged a years-long battle against the Islamic State.

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