The United States was “deeply troubled” by the conviction of a leading Turkish activist on Monday, calling his life sentence for attempting to overthrow the government “unjust,” according to the State Department.

In a statement, State Department spokesman Ned Price stated, “The United States is gravely disturbed and disappointed by the court’s decision to sentence Osman Kavala,” a critic of President Recep Tayyip Erdogan who had already been imprisoned without a conviction for more than four years.”

“His unjust conviction is inconsistent with respect for human rights, fundamental freedoms, and the rule of law,” Price added.

Washington called for the release of Kavala and “all others arbitrarily incarcerated” in Turkey, denouncing “the continued judicial harassment of civil society, media, political and business leaders in Turkey.”

A leading figure in Turkey’s civil society, 64-year-old Kavala was accused of financing protests against then-prime minister Erdogan’s government during large-scale protests in 2013 and involvement in a failed military coup in 2016. Monday’s ruling only covered the case stemming from the 2013 unrest.

Kavala’s plight had soured relations between Ankara and Western nations and Monday’s ruling from an Istanbul court has drawn swift condemnation from some of Turkey’s main allies in the NATO defense alliance as well as rights campaigners.

His treatment has prompted the Council of Europe to launch rare disciplinary proceedings that could ultimately see Turkey’s membership suspended in the continent’s main human rights grouping.