Serkan Golge, a dual US-Turkish citizen, was arrested in the aftermath of a deadly coup attempt in 2016 which left nearly 250 people dead.
US President Donald Trump thanked Turkey for the release of a US citizen imprisoned in the country for nearly three years.
Serkan Golge, a dual US-Turkish citizen, was arrested in Turkey following the deadly coup attempt in 2016 which left nearly 250 people dead.
Golge was convicted in February 2018 and sentenced to seven-and-a-half years in prison for membership in FETO [Fetullah Terrorist Organization] which was responsible for the 2016 coup attempt.
Ankara also accuses FETO of being behind a long-running campaign to overthrow the state through the infiltration of Turkish institutions, particularly the military, police, and judiciary.
The two NATO allies, Ankara and Washington, are at odds over a range of issues including America's Syria policy that saw the US support PYD/YPG, the Syrian branch of the PKK terrorist group, extradition of US-based FETO leader Fethullah Gulen, and Turkey's procurement of Russia’s S-400 missile defence system.
After having been convicted, Golge's sentence was later cut to five years by an appeals court and he was found guilty of aiding a terrorist organisation rather than being a member of one.
"...following this decision I was eligible to be released on a probational basis," Golge said on Thursday.
The State Department declined to discuss why he was released.
Tensions between the US and Turkey have reached a fever pitch in recent months with Turkey set to begin receiving the advanced S-400 Russian surface-to-air missile system which Washington said will jeopardise Turkey's role in the US F-35 fighter jet program and could trigger congressional sanctions.
In Syria, the US has supported the PYD/YPG, despite Turkey repeatedly raising security concerns after the announced withdrawal of American troops from the country in February, saying the pullout would give room for the terrorist group to expand operations.
In its more than 30-year terror campaign against Turkey, the PKK – listed as a terrorist organisation by Turkey, the US and the EU – has been responsible for the deaths of nearly 40,000 people, including many women and children.
Another standing issue is FETO. Turkey has repeatedly called on the US to extradite its leader, Fetullah Gulen, to Turkey to face trial for attempting to undermine the government by orchestrating the July 15, 2016 coup attempt.