President Donald Trump early Friday thanked Iran for the release of Michael White, an American held in Iran, and tweeted that this “shows a deal is possible”.

This is the second time Trump thanks Iran for negotiating a prisoner release and arguing that this could be a model for wider talks. Last December when Xiyue Wang, a Chinese-American researcher was released Trump thanked Tehran, tweeting, “Thank you to Iran on a very fair negotiation. See, we can make a deal together!"

White was detained in July 2018 while on a private visit to Iran and last year was convicted to 13 years in prison on a charge of insulting the Supreme Leader, a vague accusation often thrown at political detainees.

Trump has been eager to show that he is at the forefront of efforts to free Americans held abroad. In his tweet following White’s release he said, “We have now brought more than 40 American hostages and detainees back home since I took office. Thank you to Iran, it shows a deal is possible!”

Although both Washington and Tehran earlier in the week denied any deal over release of prisoners, later both admitted that White’s release was the result of talks and an Iranian charged in the U.S. can return to his country.

While for two years the Trump administration has followed a policy of “maximum pressure” on Iran over its military ambitions and anti-Western foreign policy, Tehran has refused to enter talks to resolve differences.

With a serious economic crisis precipitated by U.S. sanctions, Iran’s Supreme Leader Ali Khamenei has forbidden any talks with Washington. Observers believe Tehran is biding its time and waiting for U.S. presidential elections.

A White House spokesman quoted by Reuters expressed hope that White's release could lead to an opening in the bitter relationship. Another source said the negotiations to get White released followed several months of discussions with Iran, said a person familiar with the matter.