WASHINGTON (Reuters) - U.S. Defense Secretary Mark Esper defended the Navy’s controversial decision to remove the commander of a coronavirus-stricken aircraft carrier, who was reported on Sunday to have tested positive for COVID-19 as the number of its sailors with the highly-contagious disease also grew.

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Captain Brett Crozier started showing symptoms of the virus before he was relieved of his command of the Theodore Roosevelt on Thursday and has tested positive, the New York Times said, citing two Naval Academy classmates who are close to Crozier.

The Navy did not immediately respond to a request for comment but does not usually discuss individual cases due to privacy laws. The Pentagon also did not immediately respond.

Acting U.S. Navy Secretary Thomas Modly removed Crozier after a scathing letter written by the commander urging the Navy to do more to halt the spread of the potentially lethal virus aboard the nuclear-powered carrier was leaked to the media.

The move sparked intense backlash as videos posted on social media showed sailors aboard the vessel cheering Crozier as he departed and an online petition called for his reinstatement. It has also become a political lightning-rod as the Trump administration faces intense criticism for its handling of the nation’s coronavirus outbreak.

Esper, in his first public comments on the issue, on Sunday said he backed the dismissal.

“Secretary Modly made a tough decision, a tough call. I have full faith and confidence in him and the Navy leadership, and I support their decision,” Esper told ABC News’ “This Week” program. “This is a chain of command issue. It’s an issue of trust and confidence in the captain of the ship.”

Modly last week told Reuters Crozier was being reassigned while the Navy weighed possible disciplinary action, adding that the commander’s letter was shared too widely and was in the press before he could even read it.

On Saturday, President Donald Trump described the letter as “not appropriate” and said Crozier had done a “terrible” thing.

Former U.S. Vice President Joe Biden, a Democrat who is seeking to challenge the Republican Trump in the Nov. 3 presidential election, called the firing of the captain “close to criminal.”

“The idea that this man stood up and he said what had to be said, got it out that ... his Navy personnel were in danger,” Biden told ABC News separately. “The guy, he should have a commendation rather than be fired.”

A group of Democratic U.S. senators have also called on the Pentagon’s independent Inspector General to investigate the dismissal.

The Navy on Saturday said 155 Theodore Roosevelt sailors have now tested positive for the coronavirus but none have been hospitalized, with 44% of the ship’s nearly 5,000 crew having been tested so far.

The carrier, whose home port is in San Diego, was at sea when the outbreak began and has since docked at a U.S. naval base on Guam, allowing sailors to evacuate and be quarantined on the American island territory in the western Pacific.