President Moon Jae-in on Thursday instructed the military to dispatch medical staff and supplies to forces abroad with members who have tested positive for the coronavirus and to take stronger steps to avoid infections in overseas missions.

Moon asked the military to bring home the patients if necessary.

Six service members aboard the anti-piracy Cheonghae Unit operating off the coast of Africa have tested positive for the coronavirus, the military said. None of the 301-strong crew aboard the 4,400-ton destroyer were vaccinated, as they left the country in February, a month before the vaccination campaign started.

“We had many complaints of cold symptoms Saturday and we ran COVID tests on six of them Tuesday. They all tested positive,” a senior Joint Chiefs of Staff official said.

One seaman exhibited cold symptoms a day after the vessel left a nearby port on July 1, where it had stopped for four days for supplies, but he was treated with cold medicine and was not tested for the coronavirus, the official said.

Meanwhile one officer who showed pneumonia symptoms after he had helped load supplies was transferred to an undisclosed local hospital and is awaiting COVID test results, the official added. The military suspects the virus spread onto the ship from the port.

The military, which noted it was placing about 80 seamen in quarantine as a precaution, said it was seeking ways to test every service member on board with the help of South Korean diplomatic missions nearby, and plans to fly aerial tankers to bring home the infected personnel.

The Korean naval unit, which joined a global anti-piracy campaign in the Gulf of Aden off the Somali coast in 2009, has since rotated its troops, which include special forces, every six months. The next contingent set to take over has all been vaccinated.

About 72 percent of some 1,300 South Korean soldiers deployed overseas have received COVID-19 vaccinations, the military said.