ISTANBUL — A major Turkish military operation to eradicate Kurdish militants in Turkey’s restive southeast has turned dozens of urban districts into bloody battlefields, displacing hundreds of thousands of civilians and shattering hopes of reviving peace as an old war reaches its deadliest level in two decades.

Over the past week, Turkish tanks and artillery have pounded Kurdish targets across several southeast cities, killing at least 200 militants and more than 150 civilians, according to human rights groups and local officials.

Their descriptions of the fighting and mass destruction in populated areas, which are off-limits to journalists, depict war zones not unlike the scenes in neighboring Syria to the south.

The Kurds are a geographically dispersed minority whose aspirations for autonomy date back decades. The flaring of their conflict with Turkey represents a dangerous complication in a region already convulsed by the upheavals in Syria, Iraq and Yemen. About half of all Kurds live in Turkey, a NATO member and American ally.