Police in Turkey on Sunday arrested at least 448 suspected Islamic State members in nationwide raids. The police operation is the biggest in the country since the attack on an Istanbul nightclub on January 1, in which 39 people were killed, AFP reported. The Islamic State group had said that they had carried out the attack to avenge deaths in Syria at the hands of Turkish military forces.

At least 150 Syrians were among those arrested, with several other people being picked up from regions bordering Syria. Sixty suspects, mostly foreigners, were arrested from four districts in Ankara. Dozens of other arrests were made in the eastern and western provinces of the country. Former Turkish diplomat Sinan Ulgen said the raids represented a change in strategy by the country’s police, who have till now only detained small numbers of suspected militants.

However, the arrests may not lead to any prosecutions, as the country’s efforts against the Islamic State “is still handicapped by discrepancies between the different arms of the Turkish state” Ulgen said, according to The New York Times. Former counterterrorism official Ahmet Yayla also questioned the effectiveness of the raid, saying that it could overwhelm the police’s operational capacity. “It is impossible to process that many terrorists in one operation,” Yayla said.

The attack on the Reina nightclub is the first such incident in Turkey that the Islamic State has claimed responsibility for, even though the group has been blamed for several bombings in 2016. The main suspect in the shooting was arrested on January 17. Abdulkadir Masharipov, an Uzbek national, was arrested from the Esenyurt district in Ankara. The Turkish police had detained 35 people in connection with the incident before arresting Masharipov.