Tokyo lodged a strong protest Friday with Beijing after confirming that a submarine that intruded into Japan's territorial waters off Okinawa earlier this week belongs to the Chinese Navy.
Foreign Minister Nobutaka Machimura summoned Cheng Yonghua, Chinese minister to Japan, to the Foreign Ministry and demanded an apology for the roughly two-hour intrusion that took place near the Sakishima Islands, about 400 km southwest from Okinawa Island.
"I strongly protested to the Chinese government and demanded an apology," Machimura told a news conference after the hastily arranged meeting with Cheng.