Tokyo — Japan announced on Friday that it was bringing back COVID-19 restrictions in three states, or prefectures, as the country grapples with its sixth wave of coronavirus infections, spurred by the Omicron variant. The new “quasi-state of emergency” was to take effect on January 9 and last at least until the end of the month, primarily urging bars and restaurants to close early.

Local leaders in the affected regions are blaming American troops based in Japan for a huge spike in cases.

Thanks to some of the world’s toughest border restrictions and near-universal mask use, Japan had managed to keep the Omicron variant under control and cases low. But over the last few days, infections have surged in areas that host American military bases, including Okinawa, as U.S. troops – who had been exempt from strict Japanese entry requirements — returned from vacations in the U.S.

After recording only a handful of cases in December, Okinawa topped 1,400 infections this week alone.

Okinawa Governor Denny Tamaki, who has long called for a downsizing of the U.S. military presence on his island, blamed the American troops for the COVID surge.

The U.S. military command in Japan has so far resisted calls, including from the country’s Foreign Minister, for base lockdowns, instead adopting compulsory mask-wearing and ordering troops to follow Japanese rules for foreign travel, meaning American troops now have to test and quarantine upon entering the country, just like anyone else.

Japan had been counting on its tough border controls to keep the pandemic at bay for another month, but the sudden spike around American bases has apparently caught Tokyo off guard, and left leaders scrambling for solutions.

The measures being reimposed in Okinawa, a southern Japanese island, and in the western prefectures of Hiroshima and Yamaguchi, represent the first return to restrictions in Japan since September, when officials lifted controls that had been in place across the country for a year.

The Omicron variant has been detected in about 80% of Japan’s prefectures, and the number of new infections across the country was expected to surpass 5,000 on Friday, compared to a daily average last month of only about 200 cases.

“We must be prepared for the rapid spread of infection,” Health Minister Shigeyuki Goto told reporters on Friday, citing Omicron’s advance. “There are cases where there is no history of overseas travel and the route of infection is unknown, while the Delta strain also continues to spread.”