Was a plan to overthrow Turkey’s government really hatched behind a gated compound in a small, leafy Pennsylvania town, or is that merely a smoke screen?

In the throes of a military coup attempt, Turkey’s embattled president, Recep Tayyip Erdogan, pointed the finger of blame squarely at his bitter rival: Fethullah Gulen.

At the center of this rivalry, a fundamental division in Turkish society between secularists — some within the country’s top military brass — and Islamists, including Erdogan’s AKP party.

It’s this division that’s destabilizing one of America’s most important allies in the Middle East.

And at the center of all this is Gulen, a reclusive cleric who leads a popular movement called Hizmet.

Who is this mysterious man in Pennsylvania?

The 75-year old imam went into self-imposed exile when he moved from Turkey to the United States in 1999 and settled in Saylorsburg, Pennsyvlania.

He rarely speaks to journalists and has turned down interview requests from CNN for more than four years.

Supporters describe Gulen as a moderate Muslim cleric who champions interfaith dialogue. Promotional videos show him meeting with Pope John Paul II in the Vatican in the 1990s. He also met frequently with rabbis and Christian priests in Turkey.

Gulen has a loyal following — known as Gulenists — in Turkey, who all subscribe to the Hizmet movement.

Hizmet is a global initiative inspired by Gulen, who espouses what The New York Times has described as “a moderate, pro-Western brand of Sunni Islam that appeals to many well-educated and professional Turks.” Nongovernmental organizations founded by the Hizmet movement, including hundreds of secular co-ed schools, free tutoring centers, hospitals and relief agencies, are credited with addressing many of Turkey’s social problems.

The preacher and his movement also spawned a global network of schools and universities that operate in more than 100 countries.

In the United States, this academic empire includes Harmony Public Schools, the largest charter school network in Texas.

Within Turkey, volunteers in the Gulen movement also own TV stations, the largest-circulation newspaper, gold mines and at least one Turkish bank.