A Navy statement said at least 17 members of the crew of a destroyer, the USS Kidd, have tested positive and it expects the number to grow.
It said it is evaluating the extent of the outbreak aboard the ship.
The Kidd is in the Caribbean, where it has been operating as part of a counter-drug mission.
One sailor who displayed symptoms was flown off the Kidd on Thursday to a medical facility at San Antonio, where he tested positive for the virus.
"As a result, the Navy has - using lessons learned from other cases - flowed a medical evaluation team onto the Kidd" to conduct more testing, Pentagon spokesman Jonathan Hoffman said.
"They are preparing to return to port, where they will undertake efforts to clean the ship" and remove a portion of the crew.
The Navy continues to struggle with a coronavirus outbreak aboard the USS Theodore Roosevelt, an aircraft carrier that is docked in Guam and has more than 800 confirmed virus cases. (AP) IND