At the crossroads between a divided Europe and a convulsed Middle East, Turkey is caught in a power struggle between former Islamist allies which is shaking democratic institutions and raises questions about its future path.
Turkish President gains upper hand in power struggle
Gulen, 75, denies plotting against the state and suggested the day after the abortive coup that it may have been staged to justify a crackdown on his followers.
Since a failed coup on July 15, the ruling Justice and Development Party (AKP) founded by President Tayyip Erdogan has gained the upper hand in its battle with clandestine networks in the military, judiciary and bureaucracy loyal to U.S.-based cleric Fethullah Gulen.
This fight to the bitter end has alarmed the West and unsettled the country of 80 million, which borders the chaos in Iraq and Syria and is a Western ally against Islamic State.
Erdogan accuses Gulen of masterminding the attempted coup by a faction within the military and has rounded up more than 60,000 people in an operation which he hopes will cleanse Turkey of what he calls the Gulenist "virus".
The purges, carried out as Turkey faces attacks by Islamist State and a revived struggle with Kurdish militants, go beyond the more than 100 generals and 6,000 soldiers held, or the nearly 3,000 judges detained.
They already encompass 21,000 teachers and much of the academic community, and new targets in a media already hit by years of firings and fines, jailings and closures.
"They are traitors," Erdogan told Reuters in an interview on Thursday. He described Gulen's network as "like a cancer" and said he would treat them like a "separatist terrorist organisation" and root them out, wherever they may be.
The millions of members of Gulen's "Hizmet" (Service) movement do not outwardly identify as supporters. Since the failed coup many are going even further underground, refusing to take calls or trying to leave the country.
Some followers are dumping books in the woods and publishers are getting rid of their stocks, said Nedim Sener, an investigative journalist at Posta newspaper who wrote a book on the Gulen movement's efforts to infiltrate the state and was jailed in 2011 for more than a year.
A senior journalist at a Gulen-affiliated newspaper, speaking on condition of anonymity because he feared reprisals, said he and other editors were afraid to go to the paper's office in the days following the failed coup and that their printers refused to continue publishing.
"I advised my colleagues not to go to the office for their own safety," he said. "The newspaper has become a liability, it has just disappeared ... I'm afraid for my family and for my life. It's dangerous to go outside."
Asked if he was a follower of Gulen's teachings, he said: "Answering this question could now be used as evidence against me. Now I could be prosecuted for a book I keep at home ... Everyone is too afraid to call their friends, worried this will cause their detention. It's a climate of fear everywhere."
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