Defense Secretary Mark Esper said the US Navy was not yet "at that point" where it ought to evacuate crew members of an aircraft carrier reportedly with a growing number of coronavirus cases.

On Tuesday, the San Francisco Chronicle reported that the commander of an aircraft carrier wrote a four-page letter warning that the "spread of the disease is ongoing and accelerating."

Esper, who claimed he had "not had a chance to read that letter ... in detail," said that none of the sailors were "seriously ill."

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Defense Secretary Mark Esper said the United States Navy was not yet "at that point" where it ought to evacuate crew members of an aircraft carrier reportedly coping with over a hundred cases of the novel coronavirus.

"We are moving a lot of supplies and assistance ... out of the carrier in Guam," Esper said during an interview with "CBS Evening News" on Tuesday, referring to the USS Theodore Roosevelt and its crew of over 4,000 US service members.

On Tuesday, the San Francisco Chronicle reported that the commander of the ship, US Navy Capt. Brett Crozier, wrote a four-page letter to the Department of the Navy warning that the "spread of the disease is ongoing and accelerating."

Capt. Crozier urged that he needed a "political solution" and that the Navy needed to take "immediate and decisive action" amid the dozens of service members who were diagnosed with the coronavirus. One senior officer aboard the ship said between 150 to 200 sailors had tested positive, according to The Chronicle.

"We are not at war. Sailors do not need to die," Crozier reportedly wrote. "If we do not act now, we are failing to properly take care of our most trusted asset — our Sailors."

Crozier requested quarantine rooms in Guam, where the ship is currently stationed, in addition to relocating the majority of its crew members and isolating them for two weeks. The commander emphasized that he understood the extraordinary ask, but that by not doing so would pose "an unnecessary risk and breaks faith with those Sailors entrusted to our care."

Esper, who claimed he had "not had a chance to read that letter ... in detail," reiterated to CBS News that none of the sailors were "seriously ill."

"At this point in time, we are trying to make sure that we contain the virus, that we deploy testing kits, and we get a good assessment of how much of the crew is infected," Esper said. "And then, of course, taking other measures to ensure that we can get the carrier up and ready again to continue its mission."

Esper added that he was "going to rely on the Navy chain of command ... to assess the situation."

The Navy's top civilian leader said there were inherent difficulties in evacuating thousands of sailors from the ship. Acting Navy Secretary Thomas Modly on Monday stressed that the service needed to take a "methodical" approach so that sailors "can man all those critical functions on the ship."

As of Tuesday, the Defense Department reported that 1,259 employees had contracted the coronavirus. Four of them have died, including an officer in the New Jersey Army National Guard.