WASHINGTON — Pentagon leaders anticipate that the coronavirus is likely to strike more Navy ships at sea after an outbreak aboard an aircraft carrier in the Pacific infected more than 400 sailors, a top general said Thursday.

Gen. John Hyten, vice chairman of the Joint Chiefs of Staff, said one member of the crew of the USS Theodore Roosevelt was hospitalized Thursday in intensive care on Guam, where the carrier has been docked for more than a week. He said 416 crew members are now infected and that 1,164 test results are pending.

“It’s not a good idea to think that the Teddy Roosevelt is a one-of-a-kind issue,” Hyten told a Pentagon news conference. “We have too many ships at sea. … To think that it will never happen again is not a good way to plan.”

A retired Navy admiral and former top NATO commander in Europe, James Stavridis, said he sees more trouble ahead, and not just for the Navy.

“Clearly there are more cases to come. The most recent tally on Roosevelt alone is well over 400,” Stavridis said via email. “The Navy and all the services have some hard choices ahead in terms of whether to pull units off the line to get them well or accept some level of casualties due to the coronavirus. I think it will be a case-by-case approach depending on the mission of the unit.”

Hyten said the USS Nimitz, an aircraft carrier in port at Bremerton, Washington, preparing for a Pacific deployment, has an unspecified number of crew members who have the virus.

“There’s been a very small number of breakouts on the Nimitz, and we’re watching that very closely before the Nimitz goes out,” he said. “But it’s not a huge breakout, it’s not a big spike at this point.”

Hyten said that in addition to the 416 sailors who have tested positive so far, 3,190 have tested negative. Results from tests on the rest of the crew are pending, he said. He said 2,700 crew members have been taken off the ship and are lodged “all over the island,” which is a U.S. territory. Those who have tested positive are being checked by medics twice a day.

More broadly, Hyten said the outbreak aboard the Roosevelt is an illustration that the military has to adapt.

“This will be a new way of doing business that we have to focus in on,” he said, referring to the challenge of recruiting, training, deploying and potentially conducting combat amid the pandemic. “We’re adjusting to that new world as we speak today.”

The outbreak aboard the Roosevelt began in late March and has thrust the Navy into a leadership crisis. Thomas Modly, who resigned Tuesday as acting Navy secretary, had fired the commander of the Roosevelt, Capt. Brett E. Crozier, for having widely distributed a letter urging faster action by the Navy to save his sailors.

Later, in a separate appearance, Gen. Mark Milley, chairman of the Joint Chiefs, said that despite the outbreak aboard the Roosevelt, it could be put back to sea and returned to duty relatively quickly if required by world events.

Speaking along with Hyten at the Pentagon, David Norquist, the deputy secretary of defense, told reporters the defense leaders realize the coronavirus is not going to be a short-term problem in the military.

“We’re going to need to change and adapt because even over the coming months, the virus isn’t going to go away,” Norquist said. “We’re going to have to be able to operate in a COVID environment.”

For most people, the new coronavirus causes mild or moderate symptoms, such as fever and cough that clear up in two to three weeks. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia, and death.