Where are all those ISIL militants now?

According to New York police, 29-year-old Sayfullo Saipov, of Uzbek origin, drove his pick-up truck at pedestrians and cyclists on Oct. 31, killing eight people and wounding 11.

The U.S. authorities have not yet revealed possible links between this terrorist attack and the Islamic State of Iraq and the Levant (ISIL), or any other radical groups for that matter. But Abdülgadir Masharipov - the militant who carried out the Istanbul nightclub attack early on Jan. 1, killing 39 people at a New Year party - was an Uzbek-origin ISIL militant. He is currently in jail after being arrested by Turkish police.

The Istanbul police have been busy in recent days uncovering the links of another ISIL plot. A Turkish couple - carrying Austrian passports, according to unconfirmed reports - was arrested in Istanbul over the weekend with remote control explosives loaded on a motorcycle. As the investigations deepened it was revealed that the couple might be a part of an ISIL cell that was planning a massacre at a busy Istanbul shopping mall.

The members of the cell had bought microwave ovens from different stores before bringing them back to the mall (though now filled with explosives). They said they wanted to return the items, so the ovens were all put in the mall’s safe deposit section. The militants are believed to have been planning to set off the explosives remotely, before exploding their own suicide vests in the crowd that would then have gathered, thus causing maximum loss of life.

Police are still working on the case, trying to understand what other attacks the militants were planning and how many ISIL or al-Qaeda cells are active in Turkey at present.

According to a study by the U.S.-based think tank The Soufan Center, around 1,500 people from Turkey went to Syria to join ISIL, or DAESH with Arabic initials. Some 900 have since returned to Turkey, as ISIL edges closer to defeat.

Turkey is not in the “first rank” in terms of the countries of origin of “foreign terrorist fighters,” as the jihadist militants are usually called. Russian passport-holders - including militants from Central Asia and the Caucasus such as Uzbeks or Chechens - top that list, with nearly 3,400 such foreign fighters who went to Syria to join ISIL. Saudi Arabian citizens are in the second rank with more than 3,200, followed by Jordanians, Tunisians, French and Moroccans.

However, Turkey leads the list of ISIL and other “foreign terrorist fighters” who have been able to make their way back to their country of origin. This is perhaps largely due to the 910 km-long border between Turkey and Syria. Perhaps the recent Turkish military operations into Syria have also given some militants the chance to blend in with refugees and return to Turkey.

Whatever their means of return, The Soufan Center claims that around 900 have returned to Turkey after taking part in all kinds of terrorist activities in the ranks of ISIL and similar terror groups.

While returning from his trip to Azerbaijan on Oct. 31, President Tayyip Erdoğan said the defeat of ISIL was a major current issue but after the elimination of ISIL the next target is al-Nusra, al-Qaeda’s affiliate in Syria. The Nusra Front seemed to have dissolved itself recently, but it in fact adopted another name: Hayat Tahrir al-Sham.

Hayat Tahrir al-Sham is the group that is currently confronting the Turkish ceasefire control efforts in Syria’s Idlib, in the joint operation with Russia and Iran. Turkey is also a member of the U.S.-led coalition against ISIL, despite the ongoing rift with Washington of the U.S.’s partnership with the People’s Protection Units (YPG), the Syrian branch of the outlawed Kurdistan Workers’ Party (PKK), in the anti-ISIL campaign.

Erdoğan’s statement on Oct. 31 highlighted that Turkey’s military is in Syria not only against the presence of the PKK and its affiliates, but also against ISIL and similar groups. The Turkish military presence therefore may not end after the defeat of ISIL, because of the continued presence of al-Qaeda affiliates.

But pressing questions remain for Turkey: Where are all those ISIL and al-Qaeda-trained militants now? And what are they planning against the Turkish people and others?