According to the Turkish official, it was the U.S. initiative to create the commission to solve the issue of extradition of Turkish preacher Fethullah Gülen. Turkey already agreed to cooperate within the initiative (RFE/RL).
Gülen currently resides in the U.S. Ankara has been demanding his extradition, saying he’s behind the failed military coup in Turkey. President Erdogan has repeatedly urged the U.S. to deliver the preacher as a criminal. However, Gülen condemned the attempt of the coup in his home country and denied any involvement in it.
John Kerry, U.S. Secretary of State, claimed that Washington might consider the extradition request, but for that to happen, the Turkish side has to provide the proof that would be sufficient to prove his guilt in the U.S. court.