All national dailies reported on a Defense Ministry announcement on Thursday that an MSDF patrol plane and ship detected an unidentified submerged submarine operating in the contiguous zone near Miyako Island on Wednesday afternoon and detected it again on Thursday morning in the contiguous zone near Taisho Island in the Senkakus. The MSDF also spotted a Chinese frigate sailing near Taisho Island on Thursday. The papers said the submarine appeared to be Chinese, with Yomiuri saying its course was almost identical to the frigate’s. The vessels did not enter Japan’s territorial waters and left the contiguous zone on Thursday afternoon.

Vice Foreign Minister Sugiyama summoned Chinese Ambassador to Japan Cheng Yonghua to the Foreign Ministry to file a protest and express Tokyo’s grave concern. Chief Cabinet Secretary Suga reportedly stated at a news conference on Thursday that Japan is seriously concerned because this is a move that unilaterally raises tensions. However, Suga added that there is no change in Japan’s position of improving ties with China and that Tokyo urges Beijing not to undermine the trend toward improvement in bilateral relations.

Chinese Foreign Ministry spokesperson Lu Kang reportedly said at a press briefing on Thursday that there is no reason for China to be criticized for conducting activities in waters near its territory. However, he added that Beijing is paying close attention to the positive signs by Japan for improving its ties with China.