TEHRAN, Iran (AP) — An Iranian scientist imprisoned in the U.S. is on his way back to Iran after being freed, the country's foreign minister said Tuesday.

Sirous Asgari was in the air on a flight back to Iran, Mohammad Javad Zarif said in an Instagram post.

"Congratulations to his wife and his esteemed family,” Zarif wrote.

There was no immediate word on Iranian state-run media about the flight.

Ken Cuccinelli, the acting deputy Homeland Security secretary, earlier told The Associated Press that the DHS had started to try to deport Asgari on Dec. 12 after his acquittal on charges of trying to steal sensitive trade secrets. However, he said, Iran refused to recognize him as legitimately Iranian and provide him with a validated passport until late February.

Once Asgari received the passport, DHS made several attempts to fly him back to Iran, purchasing tickets for flights on March 10, March 18, March 23, April 1 and May 1, according to Cuccinelli. Each of those flights was cancelled due to the coronavirus pandemic, he said.

Iranian officials had associated Asgari's release with U.S. prisoners held in Iran potentially being freed, something Cuccinelli had been trying to downplay.