The US has claimed the Islamic State (IS) group's Mosul finance chief fled to Turkey after the group's defeat, as it placed him on its international terrorism sanctions list.
Salim Mustafa Muhammed al-Mansur, an Iraqi who operated as the IS finance "emir" in Mosul, was said by the US Treasury Department to have "laundered and transferred money" for the group since 2015.
"Mansur was designated as a specially designated global terrorist pursuant to executive order 13224 for acting for or on behalf of IS," reads a Treasury statement.
"As of mid-2016, he was responsible for selling crude oil that IS extracted from oil fields in Iraq and Syria. As of early 2017, Mansur was an IS finance emir for Mosul who had moved to Turkey."
The treasury report lists the Turkish cities of Mersin, Istanbul and Adana, saying Mansur had previously lived in all three.
Turkey has long faced criticism over the alleged presence of IS operatives within its borders, with accusations that militants were being tacitly allowed to cross the border into Syria in order to join groups fighting the Syrian president, Bashar al-Assad. IS in Turkey
However, a series of IS attacks in the country eventually forced the ruling Justice and Development party (AKP) to crackdown on the group's networks and impose heavy restrictions on the border.
IS have so far launched 14 attacks in Turkey, including 10 suicide bombings and three shootings, with more than 300 deaths resulting.
AKP officials have yet to respond to the US allegations that Mansur is now based in the country, however.
Thomas Jocelyn, a senior fellow at the Foundation for Defense of Democracies, suggested that the US announcement of the sanctions was in part designed to nudge Turkey over Mansur's presence.
"While the Islamic State's facilitation networks inside Turkey have long been known and are sometimes disrupted by Turkish authorities, Mansur's case raises a host of questions concerning how such a senior figure could operate in the country," he wrote in the FDD's Long War Journal.
"It is possible that the American and Iraqi governments announced the sanctions placed on Mansur in order to press the Turkish government into taking action."
Relations between Turkey and the US have been strained for several years over Washington's support for Kurdish fighters in northern Syria and the refusal to extradite the Pennsylvania-based preacher Fethullah Gulen.
Turkey blames Gulen for the failed July 2016 coup attempt and while they hoped the Trump administration would be more amenable to Turkish interests, so far there has been no movement.
The US is currently supporting the Syrian Democratic Forces (SDF) in Syria against IS.
The largest contingent of the SDF is made up of the People's Protection Units (YPG) who are affiliated with the Kurdistan Workers Party (PKK), a group involved in a long-running war with the Turkish state.