A U.S. Navy warship has paused its deployment to South America because of a coronavirus outbreak, the Navy said Friday.

The USS Milwaukee, a litorral combat ship, is staying in port at Naval Station Guantanamo Bay, where it had stopped for a scheduled port visit. It began its deployment from Mayport, Fla., on December 14 and was heading into the U.S. Southern Command region.

The Navy said in a statement that the ship’s crew is “100% immunized” and that all of those who tested positive for COVID-19 have been isolated on the ship away from other crew members. The number of crew testing positive was not disclosed. The ship has a crew of a little more than 100.

The Navy said that “a portion” of those infected are having mild symptoms, and that the specific variant is not yet known. COVID-19 cases have surged across the country as a result of the highly contageous omicron variant.

“The ship is following an aggressive mitigation strategy in accordance with Navy and CDC guidelines,” the Navy said.

The first major military outbreak of the virus was early last year on a Navy warship, the USS Theodore Roosevelt, an aircraft carrier that was operating in the Pacific. The Roosevelt was sidelined in Guam for nearly two months, and more than 1,000 of the 4,800 crew members tested positive. One sailor died, and the entire crew went through weeks of quarantine in a rotation that kept enough sailors on the ship to keep it safe and running.

According to the latest data released by the Navy, more than 98% of all active duty sailors have been fully vaccinated.