DAVID GREENE, HOST:
Turkish officials are vowing to hit ISIS harder after the group claimed responsibility for an attack at an Istanbul nightclub over the weekend. Authorities have not found the person who shot and killed 39 people at that club, but they do think they know who it is. The country's state-funded TRT World news channel is showing images of a passport identifying the suspect. From Istanbul, here's NPR's Peter Kenyon.
PETER KENYON, BYLINE: The passport is from the Central Asian country of Kyrgyzstan and belongs to a 28-year-old man named Lakhe Mashrapov. The picture matches a selfie video released by authorities Monday. Police raids have continued in neighborhoods around Istanbul since the deadly attack. Deputy Prime Minister Numan Kurtulmus says investigators are going beyond identifying the main suspect to look for anyone else that may have been supporting him.
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NUMAN KURTULMUS: (Through interpreter) So we will continue with the identification of this person and not only this person but his possible links and any other supporters that might have helped him and of course the forces behind the attack.
KENYON: The claim of responsibility by ISIS prompted Kurtulmus to say Turkey's response will be to step up its military attacks against ISIS in northern Syria. That escalation appears to have already begun. The military tells the state-run Anatolia news agency that Turkish attacks have killed at least 18 ISIS fighters in the past 24 hours and at least 150 ISIS targets have been hit by airstrikes or tank and artillery fire in recent days. The tough response has public support, but Kurtulmus also warn Turks to be on alert for future attacks.
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KURTULMUS: (Through interpreter) This can be an attack in a nightclub or in a prayer house or in an education facility or in an office or out in the markets out on the streets. It doesn't matter.
KENYON: Turkish media say intelligence tips led to the arrest of more than 60 ISIS suspects in the days leading up to the New Year's celebration, and dozens more have been rounded up since. Eight people are being held for questioning in connection with the nightclub attack. And Istanbul residents are getting used to the sight of special forces on the city streets. Peter Kenyon, NPR News, Istanbul.