Eight foreign nationals were detained by Turkish security forces on Wednesday during an operation against the terrorist group Daesh in Istanbul.

During the operation, 12 different addresses were searched. Several organizational documents and digital materials were seized in the searches. The suspects allegedly had spent long periods of time in conflict zones in Iraq and Syria.

In 2013, Turkey became one of the first countries to declare Daesh a terrorist group.

The country has since been attacked by the terrorist group multiple times, with over 300 people killed and hundreds more injured in at least 10 suicide bombings, seven bomb attacks, and four armed assaults.

In response, Turkey launched anti-terrorist operations at home and abroad to prevent further attacks.

Turkey detained Daesh's so-called “Turkish emir,” Mahmut Özden, in August. He was planning to carry out an attack on the Hagia Sophia Grand Mosque and target politicians, nongovernmental organization (NGO) heads and other prominent figures in Turkey, according to the official investigation.

Police deciphered Daesh's encrypted messages sent by the terrorist group's ringleaders in Syria and Iraq, which featured a wide range of instructions, including kidnapping tourist groups, prosecutors and deputies, and attacking the Incirlik Air Base in Adana, as well as other plans.