WASHINGTON The release of Princeton University doctoral student Xiyue Wang after more than three years of captivity in Iran was the product of months of negotiations facilitated by the Swiss government, a senior administration official said Saturday.

The official, speaking on condition of anonymity, said he hoped the release would lead to other U.S captives being freed from Iran.

Wang was released Saturday in exchange for Iranian scientist Massoud Soleimani, who had been arrested by U.S. authorities on charges that he violated sanctions against Tehran. Those charges were dropped.

Were very happy to have our hostage back," President Donald Trump told reporters at the White House on Saturday, according to pool reports. "The whole Princeton University community is very thrilled. And there was a one-on-one hostage swap.

I think its a great thing for Iran," he said. "It might have been a precursor to what could be done.

The swap ended an ordeal that lasted more than three years after Wang, who had traveled to Iran to conduct academic research, instead was arrested and convicted as a spy.

He is now in Germany, where he will undergo a medical examination before returning to the U.S., the official said.

Wangs wife, Hua Qu of Princeton, had fought for years for her husbands release. They have a son, Shaofan, who has lived more than half his life without his father.

Our family is complete once again," Qu said on Saturday. "Our son Shaofan and I have waited three long years for this day and its hard to express in words how excited we are to be reunited with Xiyue. We are thankful to everyone who helped make this happen.

Trump in an earlier statement thanked the Swiss government for helping to achieve Wangs release.

The highest priority of the United States is the safety and well-being of its citizens, Trump said. Freeing Americans held captive is of vital importance to my administration, and we will continue to work hard to bring home all our citizens wrongfully held captive overseas.

Later, he tweeted: Thank you to Iran on a very fair negotiation. See, we can make a deal together!

Iranian Foreign Minister Mohammad Javad Zarif also thanked the Swiss.

The Trump administration worked very aggressively to get him out," said Rep. Chris Smith, R-4th Dist., who spoke with Qu on Saturday after her husbands release. It didnt just fall out of the sky. It was negotiated.

Smith, a senior member of the House Foreign Affairs Committee, earlier had delivered a note from Qu to Secretary of State Mike Pompeo to give to Trump.

Wang was studying the Qajar dynasty, rulers from 1785-1925, and learning Farsi in order to access archival material. Though he had traveled to Iran with the governments permission, he was arrested in 2016 and then convicted of espionage and sentenced to 10 years in Evin Prison, where the regime holds political prisoners.

For more than three years Iranian authorities have let him languish and kept his family, including his wife and young son, in anguish over his well-being and eventual return, said U.S. Sen. Robert Menendez, D-N.J., the top Democrat on the Senate Foreign Relations Committee.

Qu on Saturday spoke with Rep. Chris Smith, R-4th Dist., a senior member of the House Foreign Affairs Committee. Smith earlier delivered a letter from Qu to Secretary of State Mike Pompeo to give to Trump.

This has been a horrific ordeal, Smith said.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant or on Facebook. Find NJ.com Politics on Facebook.

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How the U.S. was able to win Princeton University students freedom from Iran - NJ.com