‘A deal possible!’

President Donald Trump voiced hope for progress with arch-rival Iran on Thursday after the clerical regime released a US Navy veteran and the United States freed two Iranians.

Michael White, who had contracted the coronavirus while in Iran, flew out on a Swiss military jet to Zurich where he was welcomed by a senior US official.

"I am blessed to announce that the nightmare is over, and my son is safely on his way home," his mother, Joanne White, said in a statement.

Trump said he spoke to White by telephone and voiced rare appreciation to Iran, with which the United States was close to all-out war several months ago.

"Thank you to Iran, it shows a deal is possible!" Trump wrote on Twitter.

As White was flying home, a federal judge issued an order to free an Iranian-American doctor, Majid Taheri, allowing him to go see family in Iran.

A day earlier, a more prominent Iranian -- Cyrus Asgari, a scientist arrested in 2016 while on an academic visit -- returned to Iran.

US Secretary of State Mike Pompeo, who has championed a hawkish line against the clerical regime, said Iranian authorities had been "constructive" on freeing White but urged the release of three other detained US citizens.

Tensions have soared in recent months as Trump pursued a "maximum pressure" campaign against Iran, imposing sweeping sanctions and in January ordering a drone strike that killed a top Iranian general.

Observers have seen prisoner releases as a rare way of starting dialogue between the two countries, although few expect any serious headway before the US election.