NHK reported that the U.S. Navy told the network on Thursday that five crew members of USS Theodore Roosevelt who had recovered from COVID-19 and returned to duty on the nuclear carrier have tested positive for the virus again and are being quarantined. According to the network, the five sailors returned to duty as they tested negative twice after being quarantined in Guam. However, they reportedly developed flu-like symptoms this week and tested positive for the virus again. In addition to the five sailors, several people who had close contact with them disembarked from the ship are reportedly in quarantine. The network said although the U.S. Navy is hoping to swiftly resume the operation of the U.S. carrier by returning the sailors to duty, the latest incident demonstrates the challenge of resuming normal operations.