Paul Whelan, an American imprisoned in Russia, called his family Friday morning, breaking a silence that his family called highly unusual and that led the Biden administration to express concern for his well-being.

“Paul called our parents today at around 5:30 a.m. Eastern,” Whelan’s brother, David, wrote in an email to supporters. He said that his brother did not explain why he had been out of contact for more than two weeks and failed to called home as scheduled on Thanksgiving.

Nor did Paul Whelan tell his parents why he had recently been transferred to the hospital of a Russian prison where he is serving a 16-year sentence on espionage charges that the United States calls politically motivated.

“So the call at least acts as a ‘proof of life,’ even if nothing else has been explained,” David Whelan wrote.

Consular officials with the U.S. Embassy in Moscow spoke to Paul Whelan on Friday, State Department spokesperson Ned Price told reporters. Price said that Whelan told them that he had been transferred to a prison hospital on Thanksgiving Day, but had been returned Friday to the penal colony where he is serving his sentence.

“Paul stated that he was feeling well,” Price said, adding that the unexplained transfer was not unprecedented. “We have unfortunately experienced the practice of Russian authorities to move detained American citizens without pre-notification of any sort,” he said.

Winning the release of Whelan and Brittney Griner, a professional basketball player who also is being held in a Russian penal colony after she was sentenced to nine years in prison for drug smuggling, “is something that we have been constantly working on through every available channel,” Price said.

Whelan, a former U.S. Marine who became a corporate security executive, was arrested at a Moscow hotel in December 2018 and accused of spying. He was convicted in June 2020 on espionage charges that the U.S. government says were manufactured.

The Biden administration considers Whelan and Griner tantamount to political hostages.

The extreme tensions between Washington and Moscow over the war in Ukraine have complicated efforts to win their release.

Biden administration officials have proposed that Russia release the two Americans in exchange for the release of Viktor Bout, a Russian arms dealer being held in the United States. Bout was sentenced in 2011 to a 25-year prison term for conspiring to sell weapons to people who said they planned to kill Americans.

Russia has not accepted the offer, and U.S. officials say they would continue to discuss options with the Russians through official channels.

On Wednesday, John Kirby, a National Security Council spokesperson, told reporters that the Biden administration was “deeply concerned about the lack of information and the lack of contact from Paul, and we’re working on this really as hard as we can through diplomatic channels.” Secretary of State Antony Blinken told MSNBC that he was troubled by the situation.

In his email to supporters Friday, David Whelan said he believed that the State Department’s “public display of concern also had something to do” with his brother’s call and nodded to the mental toll of tracking his brother’s situation.

“It has been a great relief to return to that baseline knowledge of ‘Paul is definitely being held hostage in a Russian labor camp’ and not have to consider worse outcomes,” he wrote.

This article originally appeared in The New York Times.

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