US vice-president Joe Biden is visitng Turkey and says the US has no interest in protecting anyone who has harmed an ally.
It comes as the US and Turkey combine to recapture a key Syrian border town from IS.
As Joe Biden arrived in the Turkish capital, Ankara, President Recep Tayyip Erdogan had a clear mesage on Fethullah Gulen, the Muslim cleric who's lived in self-imposed exile in the United States for the past 17 years.
"If a country wants a criminal in your country to be extradited, you have no rights to argue with that. You have to extradite to us, according to Article 9. The US and Turkey are strategic partners. If we are partners, keeping a person like that in your country won't bring anything to the US."
President Erdogan says the US has already received 85 packages of dossiers outlining the case against Fethullah Gulen, and Turkey will pass on more evidence linking him to the July 15 failed coup attempt.
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Turkish officials say over years, a network of Gulen supporters infiltrated the country's military and public offices to create a so-called parallel state.
Appearing with the Turkish Prime Minister, Joe Biden offered reassurance to the NATO ally.
"We are cooperating. We are cooperating with Turkish authorities. Our legal experts are working right now with their Turkish counterparts on the production of, and the evaluation of, the material and evidence that needs to be supplied to an American court to meet the requirements under our law and the extradition treaty to extradite Gulen. We have no, no, no, no interest whatsoever in protecting anyone who has done harm to an ally. None. But we need to meet the legal standard requirement."
On Turkey's recent criticism of the US and other allies for their lukewarm response to the failed coup attempt, there was this from the vice-president ....
"The United States of America did not, did not, have any foreknowledge of what befell you on the 15th. The United States of America, the people of the United States of America, abhor what happened and under no circumstances would support anything remotely approaching the cowardly act of the treasonous members of your military who engaged in this behaviour."
It's a timely show of unity.
Only hours before Mr Biden's arrival, Turkish forces launched a major operation inside Syria to clear IS militants out of the Syrian frontier town Jarablus, backed by US-led coalition warplanes.
The operation comes four days after a suicide bomber suspected of IS links killed 54 people at a wedding in a south-east Turkish city.
President Erdogan claims the free Syrian Army has now taken Jarablus back from IS.
But while there's cooperation between the NATO allies, Turkish Prime Minister Binali Yildirim has expressed reservations about US support for insurgent Kurdish fighters resisting IS in Syria.
"Turkey will never accept a new Kurdish entity on the other side of its southern borders. We see this as a substantial threat to our national security. Even though they appear to be fighting against Islamic State, the United States should know that at the end of the day, you may wipe out a terrorist organisation with another terrorist organisation but how you will defeat the other terrorist organisation will be another question."
Joe Biden has made it clear Syrian Kurdish forces fighting IS must return east of the Euphrates River.
"They cannot, will not and under no circumstances, get American support if they do not keep that commitment. Period."
It's a delicate diplomatic mission for the US Vice-President in his final months in the job.
