Turkish strikes in Syria have killed at least 31 people, according to NGOs.

Turkey carried out a series of strikes against Kurdish targets in northern Syria on Saturday evening and Sunday in retaliation for the attack in Istanbul last week.

The Syrian Observatory for Human Rights, which has extensive contacts in the region, reported casualties including Syrian soldiers, a journalist and Kurdish fighters.

The strikes mainly targeted the northern city of Kobani and its environs close to the Turkish border, including grain storage facilities near al-Malikiyahand and a power plant in the Kurdish-majority Syrian Democratic Forces (SDF) area.

“These attacks by the Turkish occupation state will not go unanswered. At the right time and in the right place, we will respond with strength and effectiveness,” the SDF said in a statement.

The Turkish operation, called “Claw of the Sword”, is aimed at “eliminating terrorist attacks in northern Iraq and Syria, ensuring border security and eliminating terrorism at its source,” the Turkish Defense Ministry said in a statement.

Turkey, whose soldiers have been occupying areas in northern Syria, has been threatening to launch a new offensive against the SDF, which it considers “terrorist” since May.