A Turkish banker was convicted Wednesday in connection with a massive scheme to help Iran evade US sanctions, in an explosive case that strained ties between Ankara and Washington.Mehmet Hakan Atilla, a 47-year-old deputy general manager at Turkey’s state-run Halkbank, was charged by US authorities with taking part in a complex scheme in which Iran traded its oil and gas for gold and food.Some of the proceeds were allegedly moved through US financial institutions without their knowledge, thereby contravening sanctions. These sanctions state that “foreign-based financial institutions or subsidiaries that deal with sanctioned banks are barred from conducting deals in the United States or with the US dollar”.Atilla has denied all charges.The trial, which lasted for almost a month in New York, has strained diplomatic relations between the US and Turkey.The Turkish foreign ministry says the US verdict is unjust and void, describing the trial as being based on fake evidence and a US interference in Turkey’s internal affairs.Atilla was found guilty of five counts of bank fraud and conspiracy to help Iran avoid US sanctions, and cleared of one count of money laundering.He was arrested in the United States in March 2017.A star witnessOn Thursday, Halbank said it always adheres to national and international regulations, insisting that Atilla has the right to appeal against a US court verdict.The federal trial hinged on the testimony of well-connected Turkish-Iranian businessman Reza Zarrab, who turned state witness after admitting his involvement in the multi-billion-dollar gold-for-oil scheme to subvert US economic sanctions against Iran.“Atilla and Zarrab devised a scheme whereby gold and phoney shipments of food were used to pay Iran for its oil and gas. This occurred over a number of years and it involved hundreds of millions of dollars,” said Jasper Mortimer.Zarrab, a prominent gold trader who was arrested in Miami in 2016, agreed to testify after striking a plea bargain to violating US sanctions. Charges against him were ultimately dropped.“They were only two of the nine people that the US justice system were looking for in connection with this. Zarrab realised he was facing many years in prison and decided to turn state witness,” said Mortimer.Zarrab’s testimony implicated former Turkish ministers and even President Recep Tayyip Erdogan in the scheme, and identified 47-year-old Atilla as a key organiser.Zarrab also said he paid tens of millions of dollars’ worth of bribes to then economy minister, Zaref Caglayan, to facilitate illegal gold transactions with Iran.Erdogan’s involvementZarrab, 34, was a key figure in a 2013 Turkish corruption scandal in which he allegedly bribed four ministers to facilitate sanctions-busting trade and other deals.In testimony in a New York court on November 30, Zarrab said he was told that Erdogan, as prime minister in 2012, and treasury minister Ali Babacan had given “instructions” to two public banks to take part in the scheme.Erdogan has repeatedly rejected the allegations, saying Turkey did not violate the US embargo on Iran and that political rivals were behind the case.“The case is not a plot against America, it’s a plot against Turkey,” Erdogan told supporters in a speech on December 5. “The case has nothing to do with law, justice or trade, it’s an acrobatic spectacle,” he said.Fallout“Turkey fears that this verdict hit its banking system and now President Erdogan has dismissed this case as political,” said Mortimer. “But what really counts is what the world banking system thinks. Turkey will need the support of international banks when it next seeks loans.”Mortimer also noted that Atilla could be considered something of a sacrificial lamb in this case and that it is possible to have sympathy for his situation.“Zarrab said in his testimony that at times Atilla did not want to go along with this scheme but was persuaded to by his superiors.”Atilla will be sentenced in April.