ISTANBUL (Reuters) – A Turkish court jailed a local employee of a U.S. consulate for nearly nine years on Thursday for aiding a terrorist organisation, a ruling the United States described as deeply disappointing and based on no credible evidence.

Metin Topuz’s trial has been a major source of tension between the two NATO allies, which are also at odds over Ankara’s purchase of Russian missile defence systems and U.S. support for Kurdish fighters in northeast Syria.

Topuz, a translator for the U.S. Drug Enforcement Administration (DEA) at the consulate in Istanbul, was sentenced to eight years and nine months for aiding a network Turkey blames for a 2016 coup attempt, state-owned Anadolu agency said.

He has already been in jail for 2-1/2 years while on trial, accused initially of espionage and trying to overthrow the government. A prosecutor said in March he should be acquitted on those charges and instead face up to 15 years in prison for membership of a terrorist organisation.

Two lawyers for Topuz were not immediately available for comment.

The U.S. embassy said it was “deeply disappointed” by the conviction. U.S. officials saw no credible evidence to support the conviction and they hoped it would be swiftly overturned, it said.

“The allegations made about Mr. Topuz’s official duties misrepresent both the scope and nature of the important work undertaken by our local staff on behalf of the U.S. government and in the promotion of our bilateral relationship,” it said.

Turkey’s own embassy in Washington said the U.S. diplomatic mission should respect the court’s judgement. The U.S. embassy’s statement on the case was “not in conformity with established rules and practices governing the roles and responsibilities of foreign diplomatic missions,” it said on Twitter.

Following Topuz’s initial detention in 2017, the two countries mutually suspended visa services.

In a 78-page indictment that included telephone calls, text messages and CCTV images, Topuz was accused of links to officials who led a 2013 corruption investigation and were later found to be members of the network of U.S.-based cleric Fethullah Gulen, blamed by Ankara for the abortive 2016 coup.

Topuz said during the trial that he contacted the individuals, who at the time held high-ranking positions in the police and judiciary, as part of his job.

Gulen has lived in self-imposed exile in Pennsylvania since 1999, and has denied any involvement in the coup attempt.

The lira TRYTOM=D3 declined to more than 6.85 against the dollar after Thursday’s ruling, from around 6.8.