Japanese police arrested a US marine yesterday on suspicion of trespassing on the island of Okinawa amid anger over military crimes and demands for stricter regulations for US troops. The incident, the second after the US military had stepped up discipline last month, immediately triggered a harsh reaction from the Okinawan government. Police said Lieutenant Tomas Chanquet of the Marine Corps Air Station Futenma allegedly snuck into a room via an unlocked door and slept until a resident saw him and called police. Yesterday's arrest was especially inflammatory on Okinawa, where the Emperor Akihito was visiting to attend a fisheries event. "I'm too shocked to say anything. It's utterly ridiculous and extremely regrettable," Okinawa Governor Hirokazu Nakaima said. "I must lodge a strong protest to both the Japanese and US governments. They must do something more significant." An alleged rape by two navy sailors last month enraged Okinawans and reignited deep-rooted anti-base sentiment on the island, home to more than half the 52,000 US troops in Japan. The case led to a curfew on all troops in Japan, but two weeks later a US airman allegedly assaulted a teenager. Yesterday's incident also raises questions over the effectiveness of the curfew and other disciplinary steps. Japan has lodged a formal protest with the US embassy and US military over the incident yesterday and demanded that they make sure the curfew is enforced. Chanquet was apparently drunk when he entered the apartment, Okinawan police official Masahiko Gishi said. On Friday, Okinawa's prefectural assembly adopted a resolution protesting the two earlier cases, and demanding tougher regulations and stepped-up efforts to reduce the number of troops and bases on the island. The resolution also called for a review of legal procedures for military suspects, and efforts to streamline the US presence. Okinawans have staged massive protests against the deployment in October of Osprey military aircraft, despite opposition over safety concerns following two crashes elsewhere.