The Navy said the three sailors have not had any symptoms, and they and others who were exposed to them are currently isolated on the aircraft carrier, which is conducting operations in the Pacific. They tested positive Sunday.

In a statement, the Navy said it is “following an aggressive mitigation strategy,” including masks, social distancing, and proper handwashing and hygiene measures.

 “U.S. Pacific Fleet is committed to taking every measure possible to protect the health of our force,” the fleet said in the statement.

Also read: US COVID-19 cases hit over 14.5 mln

The outbreak on the ship last year was the largest the military has seen so far, with more than 1,000 sailors testing positive. One sailor died. Eventually all of the 4,800 crew members were sent ashore in Guam for weeks of quarantine, in a systematic progression that kept enough sailors on the ship to keep it secure and running.

The failure of the ship’s leaders to properly handle the outbreak exploded into one of the biggest military leadership crises in recent years. The ship’s captain, who pleaded for faster action to protect his crew from the rapidly spreading virus, was fired and the one-star admiral on the ship had his promotion delayed.

Adm. Mike Gilday, the chief of naval operations, concluded after a lengthy review that both men made serious errors in judgment.

Also read: Covid-19: Global cases top 108.7 million

The carrier returned to duty about three months after it docked in Guam and then returned home to the West Coast. Other ships that have been underway or at their home ports over the past year have had smaller numbers of sailors test positive, but none have had such a major outbreak.

Also read: Global Covid cases near 108 million

The Roosevelt has been out on deployment in the Pacific in recent weeks, and about a week ago conducted dual carrier exercises with the USS Nimitz, which is returning home to the West Coast from a lengthy deployment in the Middle East.