Business Insider reports: A Kurdish militia with ties to an organization waging an insurgency in Turkey’s southeast region violated Turkey’s “red line” in Syria over the weekend by crossing the Euphrates River during an anti-ISIS operation.

The operation to take back Tishrin Dam from ISIS was staged by the Western-backed Syrian Democratic Forces and spearheaded by the Kurdish YPG — the military arm of the Kurdish Democratic Union Party (PYD).

It served as a huge blow to ISIS, which had relied on the dam to move weapons and fighters between its de-facto capital of Raqqa in Syria and the cities of Manbij and Jarablous it controls in the northern countryside of Aleppo Province.

But ISIS was not the only loser. The operation was also a major affront to Turkey, which declared the Euphrates a “red line” for Kurdish territorial expansion over the summer. Indeed, Turkey struck the YPG twice in October after it defied Ankara’s warning not to cross the river. [Continue reading…]