Captain Brett Crozier addresses the crew for the first time as commanding officer of the aircraft carrier USS Theodore Roosevelt during a change of command ceremony on the ship's flight deck in San Diego, California, U.S. November 1, 2019.

A since-fired Navy captain's plea for help with a coronavirus outbreak on his vessel "was terrible," President Donald Trump said Saturday.

The officer, Capt. Brett Crozier of the USS Theodore Roosevelt, wrote a letter earlier this week to military leadership asking for help with a coronavirus outbreak on the warship. The letter, which was dated March 30, was sent via nonsecure unclassified email and also outside the chain of command. It leaked to the media.

"I thought it was terrible what he did, to write a letter. This isn't a class on literature. This is a captain of a massive ship that's nuclear-powered," Trump said at a news briefing Saturday evening. "The letter was a five-page letter from a captain, and the letter was all over the place. That's not appropriate. I don't think that's appropriate."

In the four-page letter, which was first reported by the San Francisco Chronicle, Crozier described a worsening coronavirus outbreak aboard the warship, a temporary home to more than 4,000 crew members. More than 100 people on the ship were infected at the time.

"We are not at war. Sailors do not need to die. If we do not act now, we are failing to properly take care of our most trusted asset — our Sailors," Crozier wrote in the letter. "The spread of the disease is ongoing and accelerating."

The outbreak occurred after a completed port call to Da Nang, Vietnam earlier in March. Fifteen days after leaving Vietnam, three sailors from the USS Roosevelt tested positive for the virus. The infections were the first reports of coronavirus on a military vessel at sea.