A single-day record of 235 COVID-19 cases among U.S. forces in Okinawa Prefecture was confirmed Saturday, local officials said, following a cluster infection that broke out last month at one of the U.S. bases there.
Whether the cases were of the Omicron variant, a highly transmissible strain, was unknown, as was the breakdown of the U.S. bases affected. The cumulative number of COVID-19 cases related to the U.S. military has now reached 3,613.
Japan's border control measures have come under scrutiny in the wake of a group infection at the U.S. Marine Corps' Camp Hansen in the southern island prefecture, which hosts the bulk of the U.S. military facilities in the country.
Over 250 people were known to have been infected with the coronavirus at the base.
A prefectural official called on the U.S. forces to take thorough antivirus measures, warning that an increase in infections at bases would raise the risks for nonmilitary personnel working there.
On Friday, the Foreign Ministry said the U.S. forces in Japan now require all of their personnel to test for COVID-19 within 24 hours after their arrival in the country.
Under an agreement between Japan and the United States, quarantine measures for U.S. military personnel on arrival are carried out by the United States, which means they are not subject to Japanese quarantine rules at airports.
The Japanese government has said the U.S. Defense Department had exempted its personnel from undergoing PCR tests because of the progress in vaccinations in the military and lower infection cases globally.
The forces have said the exemption began in September for vaccinated personnel coming to their facilities in Japan by military aircraft. Since the cluster infection, they have required their personnel coming to Japan to undergo the testing 72 hours ahead of departure.
Meanwhile, Tokyo reported on Saturday 79 new COVID-19 cases, the highest number since early October, continuing a gradual rebound amid the spread of Omicron. The Japanese capital is one of the areas to have reported a community spread of the variant.
In late November, Japan implemented strict border controls to stop the Omicron variant from entering by banning the entry of nonresident foreign nationals. It has also toughened quarantine measures for Japanese citizens and foreign residents who have recently been to certain countries or regions.