Turkish Prime Minister Binali Yildirim has threatened war against any country that would “stand by” Turkish cleric Fethullah Gülen.

This is a pointed threat towards the United States, where Gülen has been living in self-imposed exile since 1999. The implicit demand, according to BBC’s Turkey correspondent Mark Lowen, is that the US must extradite Gülen.

Gülen is the leader of a movement called Hizmet, and has been called Turkey’s second most powerful man. Hizmet is estimated to have the support of 10% of Turkey’s population, and Turkey’s president Recep Tayyip Erdogan claims Gülen was behind the recent attempted coup.

But the cleric has strongly denied that this is the case and the US has asked Turkey for evidence to support the accusations.

If Turkey can prove Gülen was behind the failed coup, then the US secretary of State John Kerry said the Obama administration would consider an extradition request.

On July 16 Gülen told the New York Times he was against the coup. “I condemn, in the strongest terms, the attempted military coup in Turkey. Government should be won through a process of free and fair elections, not force,” he said. “As someone who suffered under multiple military coups during the past five decades, it is especially insulting to be accused of having any link to such an attempt. I categorically deny such accusations.”

A few days ago, before the coup attempt, Turkey said it was preparing an extradition request to send the US. But, according to Reuters, the US says it has not yet received any such requests.