Fethullah Gülen is a bit of a mysterious character. But from the little I know, he is every bit as much an Islamic infiltrator and subverter as is Erdogan, lives in the US, has deep roots in the US administration and I believe runs a series of schools in the US where kids are taken to Turkey on field trips where no parents are allowed, and given intensive courses on Islam.
Erdogan has had a personal vendetta against Gulen for some time now.
Erdogan blamed the uprising on Fethullah Gulen, a retired Islamic cleric and former political ally, who once had a sizable following in the Turkish police, judiciary and military. Erdogan, who has purged the police and judiciary of reputed Gulen sympathizers over the past two years, had been due to hold a meeting of the body overseeing the military, the High Military Council, and there were reports he was planning oust anyone still linked with Gulen.
Gulen now lives in exile in Pennsylvania, and Erdogan has tried, thus far unsuccessfully, to obtain his extradition to face allegations of supporting terrorism.
More as it comes in.
If the coup fails we will probably never learn who was behind it.