On Thursday, the US president confirmed that former US Navy veteran Michael White had been released after spending over a year-and-a-half incarcerated in an Iranian jail, and boasted that over 40 US ‘hostages and detainees’ had been released since he took office in 2017.

Iranian Foreign Minister Mohammad Javad Zarif has challenged President Donald Trump’s telling of how imprisoned US Navy veteran Michael White was able to come home, tweeting that Iran and the US “achieved [the] humanitarian swap *despite* your subordinates’ efforts, @realDonald Trump.”

“And we had a deal when you entered office. Iran and other [Joint Comprehensive Plan of Action nuclear deal] participants never left the table. Your advisors – most fired by now – made a dumb bet,” Zarif added, suggesting it was up to Trump to personally “decide *when* you want to fix” relations.

Zarif’s comments followed a pair of Trump tweets Thursday in which the president announced that White was “COMING HOME,” and boasted that “we have now brought more than 40 American hostages and detainees back home since I took office.”

Trump thanked Iran for agreeing to the swap, and suggested that “a deal is possible!”

White traveled to Zurich on Thursday after leaving Iran. The US national was arrested by Iranian authorities in mid-2018 during a visit to the country, ostensibly to see his partner, an Iranian woman he’d met online. He was sentenced to 10 years in prison for insulting Iran’s Supreme Leader and violating privacy laws, as well as unspecified “security crimes.” According to Foreign Ministry spokesman Abbas Mousavi, White was released “after satisfying the plaintiffs” and was granted “Islamic mercy for his other crimes.”

White was released in exchange for Dr. Majid Taheri, an Iranian physician. Taheri had been held in US custody over alleged violations of US sanctions against Tehran. Zarif also confirmed Thursday that Iranian materials scientist Dr. Sirous Asgari had reunited with his family this week after being freed from US custody. Asgari was arrested by the FBI in 2017 and accused of stealing trade secrets. The US government fought and lost its case against him in court, but continued to detain him indefinitely in the years that followed.

This week’s prisoner swamp offered a brief respite from years of strained relations between Tehran and Washington, with tensions beginning to escalate after the Trump administration unilaterally abandoned the Iran nuclear deal in 2018 and slapped the Islamic Republic with banking and energy sanctions.

Iran announced its readiness for unconditional prisoner exchanges with the US last month. Earlier, US media estimated that along with White, three US citizens of Iranian descent were being held in Iran on espionage charges, while the US was detaining about 20 Iranians.