VIENNA - The lawyer of an American-Iranian father and son jailed in Iran called on US President Donald Trump to get his officials to press for the men's release at nuclear talks with Tehran on Tuesday.An Iranian court sentenced 46-year-old Siamak Namazi and his 80-year-old father Baquer Namazi to 10 years in prison each in October on charges of spying and cooperating with the United States.The Namazis' lawyer, Jared Genser, said he had traveled to the nuclear talks venue in Vienna with Siamak's brother, Babak, to encourage Washington's delegation to press the case, adding that he was worried about the detained men's health.The lawyer said a senior administration official in the US delegation had told him on Monday that the case would be raised directly during the talks on the implementation of a deal reached in 2015 to shrink Iran's nuclear program in exchange for sanctions relief.A State Department spokeswoman did not comment directly on the case, but said: "We continue to use all the means at our disposal to advocate for US citizens who need our assistance overseas.”Iran has not commented on the Namazis' prison conditions but has repeatedly said that political prisoners are kept under standard condition in Evin prison with full access to medical care."In our view, something happening to the Namazis would be devastating not just to one side but to both sides," Genser told reporters in a hotel near the venue. "For either or both of the Namazis to die on (Trump's) watch would be a public and catastrophic failure of his negotiating skills."Iran's Islamic Revolutionary Guard Corps detained Siamak Namazi, a businessman, in October 2015 while he was visiting family in Tehran, relatives said.The IRGC arrested his 80-year-old father, Baquer Namazi, a former Iranian provincial governor and former UNICEF official in February last year, family members said.Soon after the sentencing and days before he won the presidential election, Trump said on Twitter: "Iran has done it again ... This doesn't happen if I'm president!"