WASHINGTON – An American college student whose parents say he has been in a coma while serving a 15-year prison term in North Korea was released and returned to the United States on Tuesday as the Trump administration revealed a rare exchange with the reclusive country.

An airplane carrying Otto Warmbier, who’s from Ohio, arrived in Cincinnati shortly before 10:20 p.m. Two ambulances were parked near an airport hangar.

Warmbier’s release came during a visit to North Korea by former NBA star Dennis Rodman, one of the few people to have met both North Korean leader Kim Jong Un and President Trump.

Department of State spokeswoman Heather Nauert told reporters Rodman had nothing to do with Warmbier’s release. Rodman had told reporters before arriving in Pyongyang that the issue of Americans detained by North Korea is “not my purpose right now.”

Securing Warmbier’s release “was a big priority” for President Donald Trump, who worked “very hard and very closely” with Secretary of State Rex Tillerson, spokeswoman Sarah Huckabee Sanders said.

While North Korea’s move to free Warmbier could potentially provide an opening for talks on security issues, the prospects still appear bleak. International negotiations on the dispute over North Korea’s nuclear program have been in limbo for years, as the U.S. cranks up economic sanctions and North Korea won’t give up weapons it considers a guarantee against invasion.

The detention of Americans, often sentenced to draconian prison sentences for seemingly small offenses in the totalitarian nation, has compounded tensions between Washington and Pyongyang. Three Americans remain in custody.

Otto Warmbier speaks to reporters in Pyongyang, North Korea, on Feb. 29, 2016. Associated Press/Kim Kwang Hyon

Warmbier, a 22-year-old University of Virginia undergraduate, was convicted and sentenced in a one-hour trial in North Korea’s Supreme Court in March 2016. He was sentenced to 15 years in prison with hard labor for subversion after he tearfully confessed that he had tried to steal a propaganda banner.

Tillerson announced that the Department of State had secured Warmbier’s release at the direction of the Republican president. He said Warmbier, of Wyoming, in suburban Cincinnati, was en route to the U.S.

Warmbier’s parents, Fred and Cindy Warmbier, said he was in a coma and was flying home. They said they were told he has been in a coma since his trial, when he was last seen in public, and they had learned of this only one week ago.

“We want the world to know how we and our son have been brutalized and terrorized by the pariah regime” in North Korea, Warmbier’s parents said. “We are so grateful that he will finally be with people who love him.”

In Wyoming, resident Amy Mayer said news of his release had sent waves of shock and joy through the neighborhood.

A White House official said Trump had instructed Tillerson to take all appropriate measures to secure the release of Americans held in North Korea. The official referred to them as “hostages.”

The U.S. government accuses North Korea of using such detainees as political pawns. North Korea accuses Washington and South Korea of sending spies to overthrow its government.

It’s unclear if Warmbier’s release during Rodman’s visit was purely coincidental. Rodman has traveled to the isolated nation four times since 2013, attracting a lot of publicity, much of it unfavorable. In 2014, Rodman arranged a basketball game with other former NBA players and North Koreans and regaled leader Kim with a rendition of “Happy Birthday.”

Rodman’s current trip is his first since Trump, his former “Celebrity Apprentice” boss, became president. He told reporters in Beijing, as he departed for Pyongyang, that he hopes his trip will “open a door” for Trump.

North Korea poses one of the greatest national security challenges for Trump as it tries to develop a nuclear-tipped missile that could strike America. He is looking to increase economic and diplomatic pressure on North Korea, with help from China but has said he’s open to meeting Kim.

In the past, North Korea has held out until senior U.S. officials or statesmen came to personally bail out detainees. A 2009 visit by former President Bill Clinton, a Democrat, secured the freedom of American journalists Euna Lee and Laura Ling.

Tillerson said the Department of State was continuing “to have discussions” with North Korea about the release of other three American citizens imprisoned there. They are:

• Kim Hak Song, who was detained in early May to be investigated for committing unspecified hostile acts, North Korea has said. He worked at the Pyongyang University of Science and Technology.

• Tony Kim, who also goes by his Korean name Kim Sang-duk, was detained April 22 at the Pyongyang airport. He had also taught at the university. He was accused of committing unspecified criminal acts intended to overthrow the government.

• South Korean-born U.S. citizen Kim Dong Chul, who was sentenced in April 2016 to 10 years in prison with hard labor after being convicted of espionage.