A top Syrian Kurdish leader detained on Saturday in the Czech capital Prague at Turkey’s request was freed today, prompting angry reactions from Ankara.

In a statement, the Turkish Foreign Ministry asserted that Salih Muslim’s release following a court hearing today displayed “the insincerity” of European countries in the fight against terrorism. Deputy Prime Minister Bekir Bozdag went further, claiming that freeing Muslim was a violation of international law and amounted to support for terrorism. Relations between the two NATO allies would suffer, he added.

According to Foreign Minister Mevlut Cavusoglu, Turkey sent a diplomatic note to the Czech Republic to protest the move and will continue to pursue the former co-chair of Syria's Democratic Union Party (PYD), counted among the most influential Kurdish political groupings in Syria, wherever he went. “For us, Salih Muslim is a terrorist. His release is a scandal.” Turkey has demanded that Muslim, a Syrian national, be extradited to Turkey. There were unconfirmed reports Muslim will have to wait for at least another hearing pending Turkey's submission of evidence against him before he can leave the country.

Turkey insists that both the PYD and its armed wing the People’s Protection Units (YPG), the US-led coalition’s top ally in the fight against the Islamic State (IS) in Syria, are terrorist groups that threaten its national security. On Jan. 20, Turkey launched a large-scale military operation against the YPG-controlled Afrin region and has vowed to eject the YPG from the long slab of territory it controls along the Turkish border. The accusations stem from the PYD and YPG’s allegiance to Abdullah Ocalan, the imprisoned founder of the Kurdistan Workers Party (PKK), which has been fighting on and off for Kurdish self-rule inside Turkey since 1984.