TOKYO—The United States and Japan on Sunday agreed to keep American troops within their bases amid a rise in COVID-19 cases in Japan. The restrictions starting Monday will last 14 days, confining U.S. military personnel to base facilities except for “essential activities,” a statement from the U.S. Forces in Japan said. The Japanese Foreign Ministry released the same statement. The allies will share information and cooperate on COVID-19 measures, “given the extraordinary virulence of the Omicron variant spreading throughout Japan,” the statement said. U.S. military members will wear masks, both on and off base, when outside their homes, and will continue to carry out strict testing before leaving for, and after arrival in Japan, it said. New COVID-19 cases have spiked in Japan. The spike has been most pronounced in areas near U.S. bases. Last week, Japan asked the United States for cooperation in keeping its military personnel on base. …