Kurdish forces, called the People’s Protection Units, or YPG, flaunted a mine-resistant ambush protected vehicle over social media Tuesday — an up-armored gun truck specifically designed to resist improvised explosive devices, but not previously authorized for provision to U.S.-backed forces.

The vehicle, abbreviated as an MRAP, was seen in a video posted by an official YPG Twitter account, as fighters geared up for an assault against the Islamic State near Deir ez-Zor, in eastern Syria.

The YPG make up a significant portion of the U.S.-backed Syrian Democratic Forces, or SDF, which U.S. officials have been working to coax back to fighting ISIS holdouts after they largely headed north to fend off a Turkish offensive against Kurdish fighters in Afrin, Syria.

Marine Maj. Adrian Rankine-Galloway, a Pentagon spokesman, confirmed to Military Times that the U.S. government is providing MRAPs to the Syrian Arab Coalition, which he called “an essential component of the SDF.”

“However, we cannot speak to the facts behind this photo, and will not speculate on what is depicted,” Rankine-Galloway said.

The flag flown on top of the MRAP appears to be adorned with the SDF logo, and could be manned by non-Kurdish members of the coalition, although the YPG command structure is deeply embedded within the SDF.

The U.S. military often transfers equipment to partner forces in order “to maintain an operational advantage over ISIS, which has had years to fortify their defenses with lethal barriers, obstacles and improvised explosive devices,” Rankine-Galloway added.

ISIS fighters were last reported to be focused in isolated pockets along the Middle Euphrates River Valley, according to a Pentagon briefing in April.

It remains unclear whether these MRAPs pictured with YPG fighters were passed along from the Syrian Arab Coalition or perhaps from other Kurdish forces, such as Iraqi peshmerga who were gifted roughly 250 MRAPs during their own anti-ISIS offensives in 2015.

Previously, the U.S. proxy group was only known to be authorized Humvees, Toyota Hilux trucks, Toyota Land Cruisers and Lenco BearCat armored vehicles, as well as various armored tractors and bulldozers.

Syrian Democratic Forces have also been seen running with homemade armored vehicles, as well as Russian BMP infantry fighting vehicles and Russian tanks captured from President Bashar al-Assad’s forces when the Syrian Civil War first kicked off.

U.S. military assistance to Kurdish fighters has been a source of contention with Turkey, a NATO ally. Turkey claims the YPG is aligned with the Kurdistan Worker’s Party, or PKK, which is listed as a terror group by both countries.

In order to avoid further tensions with Turkey, the Pentagon said the provision of MRAPs and other equipment is made known to Ankara’s leadership in a timely manner.

“We maintain transparency with our NATO ally Turkey, providing them with detailed and timely information about equipment and support to the SDF,” Rankine-Galloway said.

In the end, the Pentagon may be walking a thin line in relations with Turkey by providing high-tech equipment to Syrian Arabs, rather than Syrian Kurds, when both groups exist within the same SDF coalition.