U.S. President Donald Trump on December 7 thanked Iran for releasing an American postgraduate student who had been imprisoned in Tehran for over three years on charges of espionage in exchange for a prisoner held in the U.S. 

In a tweet on Saturday President Donald Trump thanked Iran for releasing American citizen Xiyue Wang and said making a deal with Iran is possible, according to CNBC.

In his tweet the U.S. President said: “Taken during the Obama Administration (despite $150 Billion gift), returned during the Trump Administration.  Thank you to Iran on a very fair negotiation.  See, we can make a deal together!”

In another tweet Trump said the United States will not rest until every American wrongfully detained in Iran and around the world was brought back home to their loved ones.

U.S. Secretary of State Mike Pompeo also thanked the Swiss government in a tweet for facilitating Wang's return and said the U.S. is "pleased the Iranian government has been constructive in this matter."  U.S. officials have repeatedly denied that Wang, who was held in Evin Prison on two counts of espionage, was a spy.

According to Radio Liberty, Xiyue Wang, a Ph.D. candidate in the Department of History at Princeton University had gone to Iran in August 2016.  He was arrested by Iranian security forces on charges of espionage while conducting research on Iranian history for allegedly seeking access to confidential areas of Tehran libraries and recording 4,500 pages of digital documents.

Wang was released in Switzerland in exchange for the release of an Iranian scientist Massoud Soleimani, who was being held in an Atlanta jail over charges of violating American trade sanctions against Iran.  He was arrested at a Chicago airport last year on trying to export biological material to Iran in violation of the U.S. sanctions.  Soleimani was expected to be released as early as January under a plea agreement.

Both men were flown to Zurich where the exchange took place. Iran's foreign Minister Mohammad-Javad Zarif travelled to Zurich himself to take Soleimani back to Iran.