The military's second-highest ranking officer on Thursday warned of a new coronavirus outbreak aboard the USS Nimitz, an aircraft carrier about to embark on a deployment to the Pacific as the military struggles to contain the spread of the virus that has already sidelined crewmembers from another carrier.

"There's been a very small number of breakouts on the Nimitz, and we're watching that very closely," Air Force Gen. John Hyten, vice chairman of the Joint Chiefs of Staff, told reporters at the Pentagon on Thursday about the 5,000-member crews. He said that those sailors have "been isolated on the ship."

Hyten pointed to the inherent problem of containing the spread of the virus, which causes a disease known as COVID-19, aboard a ship in which many crewmembers share quarters, with often more than two dozen sleeping in bunks in one room. Not enough local hotel space exists in Bremerton, Washington, where the ship is based, for its commanders to quarantine crew members, so they're attempting to isolate them on board, the general said.

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Lt. Rochelle Rieger, a spokeswoman for the Navy's 3rd Fleet, which oversees operations in the northeast Pacific region, later told U.S. News that two sailors from the Nimitz had been treated for potential COVID-19 infections. One began showing symptoms while he was on leave out of state and tested positive for the virus. That sailor was put into isolation, also out of state, having never boarded the ship during that time.

Another sailor who was on the ship took the test around March 24, but it came back inconclusive. The ship's commanders and medical staff isolated the sailor for two weeks anyway, as well as 15 other people that an investigation concluded the sailor may have encountered.

None of the sailors showed any further symptoms during the mandatory 14-day quarantine, and all, as of Thursday, were going through a process to return to duty on the ship.

On April 1, the ship went into what the Navy calls "fast cruise" status, in which no one on board was allowed to disembark for any reason. Anyone who must come aboard – such as a specialist to fix a broken piece of equipment – must first undergo medical testing and wear a protective mask while on the ship.

The ship's commanders also put into place new medical restrictions and plans to isolate anyone who feels symptoms of the coronavirus while at sea. Any sailors who show signs of having contracted COVID-19 will remain in quarantine for 14 days after they recover from any symptoms they had.

Rieger declined to comment on when the Nimitz plans to set sail.

As the crew prepares for the upcoming departure, members are under a 14-day travel restriction – limiting personal leave and isolating those who may have come into contact with a person infected by the virus – in an attempt to stem the spread, Chief of Naval Operations Adm. Mike Gilday wrote in a message to all sailors late Wednesday updating them on the effect of the coronavirus across the service.

Politico first reported the cases of the coronavirus on the Nimitz, the fourth of the Navy's 11 carriers to have documented the spread of the disease on board. The USS Ronald Reagan and USS Carl Vinson also have reports of small numbers of coronavirus cases among their crews.

Thursday's news represented a troubling problem for the U.S. military as it struggles to contain the fallout from the spread of the virus, which has affected more than 400 members of the crew of the USS Teddy Roosevelt, currently docked in Guam. Military officials continue to insist the ship is capable of deploying if needed, even though more than half of its crew has disembarked on the island to enter quarantines.

Hyten announced Thursday that one member of that carrier has been admitted to the hospital and another has entered an intensive care unit – a break from prior officials' assessments that all cases on board were relatively mild. Officials now report 416 positive cases of the coronavirus among the crew. And the problem that ship has faced will likely persist throughout the sea service.

"It's not a good idea to think that the TR is a one-of-a-kind issue," Hyten said. "To think it will never happen again is not a good way to plan."

The news comes amid a leadership crisis that led to the dismissal of the ship's captain and the resignation of the Navy's top civilian.

Then-acting Navy Secretary Thomas Modly fired the ship's commander, Capt. Brett Crozier, earlier this month after a letter became public that the captain wrote, begging for more help from the sea service to contain the spread of the virus on board. Modly on multiple occasions attempted to explain his decision, for which he faced harsh criticism, including traveling 8,000 miles to Guam to address the crew himself. He ultimately resigned on Tuesday.

David Norquist, the deputy defense secretary who spoke with Hyten on Thursday, warned America's enemies against thinking any of these issues prevents the military from responding to foreign threats.