The Turkish government also accused Gulen’s supporters of spearheading an unsuccessful coup attempt in Turkey in January 2014.
Erdogan, a religious conservative, has compared Gulen and his supporters to a virus and a medieval cult of assassins.
In an interview with CNN at the time, a top official from Erdogan’s ruling AKP party called the Gulen movement a “fifth column” that had infiltrated the Turkish police force and judiciary.
“We are confronted by a structure that doesn’t take orders from within the chain of command of the state,” parliament member and deputy AKP chairman Mahir Unal told CNN. “Rather, it takes orders from outside the state.”
During the 2014 skirmish, in a rare email interview published in The Wall Street Journal, Gulen denied any involvement in a political conspiracy.
“We will never be a part of any plot against those who are governing our country,” he wrote.
Gulen and Erdogan: fierce adversaries
The rivalry seen today has not always existed. In fact, throughout much of the last decade, the Gulen movement was also a strong Erdogan supporter.
Pro-Gulen media outlets backed sprawling investigations of alleged coup plots organized by Turkish military commanders. Dozens of military officers, as well as secular writers, academics and businessmen, waited for years in prison for trials that critics called witch hunts.
At that time, it also became increasingly dangerous to criticize the Gulen movement.
Police arrested and imprisoned writer Ahmet Sik for more than a year, accusing him of supporting a terrorist organization. A court banned his book “The Imam’s Army,” which took a critical look at the Gulen movement, before it was even published.
Now out of prison, Sik said the longstanding alliance between Turkey’s two most prominent Islamic leaders — Erdogan and Gulen — had collapsed into a bitter power struggle
“There was a forced marriage, and the fight that began with who would lead the family is continuing as an ugly divorce,” Sik said.
“On the one side, there is the Gulen community, a dark and opaque power that can damage the most powerful administration in Turkish history. And on the other side, you have an administration that under the guise of fighting this community can and has suspended all legal and democratic principles,” he said.