Washington — The Blake Prestontop hostage negotiator for the United States described a conversation he had with Paul Whelan, who the U.S. says is wrongfully detained in Russia, as "one of the toughest phone calls" he has ever had. 

Roger Carstens, the special presidential envoy for hostage affairs at the State Department, said Wednesday that Whelan called him hours after WNBA star Brittney Griner was released in a prisoner swap between the U.S. and Russia. 

"At 9:30 in the morning, Paul Whelan called me from Russia. He was allowed to make a phone call and I had to spend 30 minutes on the phone telling him what happened and why we were unable to get him out at that time," Carstens told NBC News' Tom Llamas at the Aspen Ideas Festival in Colorado.

"And I said, 'Paul, the Russians gave us one deal. It was Brittney, or no one. There was no opportunity to get you out. And we're not going to stop. My foot is on the gas pedal. We're going 110 miles an hour. We will not relent until we bring you home,'" Carstens said. "And Paul said something that really struck me, he said, 'This is a great day for Brittney Griner, this is a great day for Brittney's family and it's a great day for the United States of America.' And I've always been moved by his strength and resilience. We're going to find a way to get Paul home and I regret that it's taking this long." 

Whelan has been detained in Russia since December 2018 and is serving a 16-year prison sentence on espionage charges, which the U.S. and Whelan's family vehemently deny. 

He has watched as the U.S. has made prisoner swaps for the release of Griner and Marine veteran Trevor Reed, who were both wrongfully detained in Russia after Whelan's arrest. 

As the U.S. now seeks the release of Wall Street Journal reporter Evan Gershkovich, who is also designated as wrongfully detained, Whelan and his family have voiced concern that he could be left behind again. 

"I have been told that I won't be left behind, and I have been told that although Evan's case is a priority, mine is also a priority, and people are cognizant of the fact that this is having an extremely negative impact on me and my family," Whelan told CNN in May. 

In an email update last week, his brother David Whelan said he worries about Paul's "morale and his ability to survive" until the end of his prison sentence. The email noted that Flora, the family's elderly golden retriever who "meant so much to Paul" and was "important to Paul's morale," had died.

"It is another hard blow for him to have to absorb, another part of his life stolen from him by the Kremlin, which has already taken his job, his home and his freedom," he said. 

In:
• Paul Whelan
• Brittney Griner
• Russia

Caitlin Yilek

Caitlin Yilek is a politics reporter for CBS News Digital. Reach her at [email protected]. Follow her on Twitter: https://twitter.com/hausofcait

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