US-backed Kurdish rebels, dominated by the YPG, have claimed a significant gain over the weekend in Syria, saying they captured the Tishrin Dam on the Euphrates river, and effectively cutting off the supply route between ISIS capital of Raqqa and its Aleppo possessions.

US airstrikes were involved in the attack, and the Kurds claimed an offensive involving thousands of fighters. It’s unclear if this means they captured the entirety of the damn complex, or simply some of it, as the dams tend to be a bit isolated, and amid fighting the actual status is often hard to discern.

Indeed, fighting over dams in Iraq has at times led to false claims from multiple factions to all control the same dam at the same time. Whatever the case this time, the Kurds are making a major push, and seizing some significant territory along the river.

The dams are important both because they allow forces to control the flow of water into important cities, and because in some cases they are major generators of electricity. Indeed, much of the electricity in ISIS territory is generated by a handful of hydroelectric dams.