This article first appeared on the Atlantic Council site.

Relatives of an imprisoned Iranian-American father and son are urging the Trump administration to open a direct channel to the Iranian government to discuss trading the detainees for Iranians imprisoned for sanctions violations.

“It shouldn’t be another tragedy like Otto Warmbier,” Babak Namazi said Wednesday on a conference call. He was referring to the American student arrested by the North Koreans in 2016 who was returned in June to the United States in a coma and died days later.

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Babak’s father, Baquer, is 81 years old and suffers from a severe heart condition. In September, he was taken to a hospital from Tehran's Evin prison, where he has been incarcerated since February 2016, and fitted with a pacemaker.

“I want no efforts to be spared because of the time issue,” Babak said, suggesting that his father could not survive many more months of captivity.

Baquer and Babak’s brother, Siamak, were convicted last year on charges of espionage that are widely considered bogus and sentenced to 10 years in prison.

The family had sounded relatively optimistic a few months ago about the chances to gain their relatives’ release, but an element of impatience was evident Wednesday in their comments about the Trump administration.

Iranian Foreign Minister Javad Zarif has stated several times that Iran is ready to begin a conversation about swapping the Namazis for about a dozen Iranians jailed in the US and overseas at US request for violating nuclear-related sanctions that have been lifted under the Joint Comprehensive Plan of Action (JCPOA), noted family lawyer Jared Genser. But the Trump administration has not directed anyone to begin formal talks with the Iranians about a prisoner exchange.

Among those mentioned by Zarif is a personal friend of his, Ahmad Sheikhzadeh, who had worked as a consultant to the Iranian Mission to the United Nations, where Zarif served as ambassador a decade ago. Zarif also spoke in July of an Iranian woman who was pregnant and jailed for sanctions infractions in Australia.

Asked whether the Trump administration’s recent decision to decertify the JCPOA and its belligerent rhetoric toward Iran had interfered with their efforts to secure the Namazis’ release, Genser said, “This is a humanitarian question, not a political question. We would hope that both sides have an interest in getting their people back.”

“We are always concerned when rhetoric is raised but at the end of the day this is a humanitarian case,” Babak underlined. “An old man with heart ailments could die in prison.”

Genser said that the Trump administration had talked directly to North Korea to secure Warmbier’s release, albeit too late to save his life.

Babak Namazi, the brother and son of two prisoners in Iran, who hold both U.S. American and Iranian citizenship and who have been sentenced to lengthy prison terms in Iran, in Vienna, Austria, April 25, 2017. Leonhard Foeger/reuters

“If you can talk to the government of North Korea, you can talk to the government of Iran,” Genser said.

Barbara Slavin is director of the Future of Iran Initiative at the Atlantic Council.