ERBIL, Kurdistan Region of Iraq - US Secretary of State Antony Blinken on Friday asked Turkey to work against any possible Islamic State (ISIS) resurgence in Syria, as Ankara assured Washington that it would not allow any let-up in the fight against ISIS  in the wake of Bashar al-Assad’s shocking ouster. 

"Our country worked very hard... to ensure the elimination of the territorial caliphate of ISIS (IS), to ensure that that threat doesn't rear its head again," Blinken said in Ankara at a press conference with Turkish Foreign Minister Hakan Fidan.

Blinken told Turkey that it was "imperative that we keep at those efforts."

Blinken arrived in Ankara late Thursday where he met with President Recep Tayyip Erdogan, holding an hour-long meeting at the airport to discuss the latest developments in Syria.

Erdogan told Blinken that Turkey would not ease up in the fight against ISIS, but would take “preventive” measures against Kurdish forces which Ankara views as an extension of the Kurdistan Workers Party (PKK). 

"Turkey will never allow any weakness to arise in the fight against ISIS," Erdogan told him, according to a statement from his office. 

Erdogan also said that Ankara would take "preventive measures against all terrorist organizations, primarily the PKK/PYD/YPG and ISIS (IS) terrorist organizations, operating in Syria and posing a threat to Turkey, primarily for its own national security”.

The US-backed, Kurdish-led Syrian Democratic Forces (SDF) currently control the bulk of northeastern and eastern regions of Syria, amounting to a quarter territory of the country. Formed in 2015, the SDF is considered the Kurdish de facto army in Syria.

Turkey considers the YPG, which is the backbone of the SDF, as inextricably linked to the PKK. The YPG, however,insists that they merely subscribe to similar ideology.

The PKK is an armed group that has fought for increased Kurdish rights in Turkey for decades. The group is designated a terrorist organization by Ankara.

The US currently has over 900 troops based in Syria who provide military support to SDF in the fight against ISIS.

Blinken’s visit to Ankara came as the US on Tuesday brokered a ceasefire between the SDF forces and Turkey-backed Syrian opposition groups who controlled the city of Manbij and Til Rafaat from the earlier’s control following heavy clashes. 

Parallel to a lightning offensive spearheaded by the Hay’at Tahrir al-Sham which took less than two weeks to end over half a century of the Assad family’s rule in Syria, Turkey-backed groups attacked areas under the control of the Kurdish forces.

Though Washington has repeatedly acknowledged Turkey’s security concerns, Blinken said Thursday that the SDF was "critical" to preventing an ISIS resurgence.

“We want to avoid sparking any kinds of additional conflicts inside of Syria," Blinken told reporters in Aqaba, Jordan, before departing to Ankara. 

"And part of that also has to be ensuring that ISIS doesn't rear its ugly head again. And critical to making sure that doesn't happen is the so-called SDF, the Syrian Democratic Forces, that we've been supporting," he said.