After meeting briefly on the sidelines of the APEC summit in Lima, Peru, last month, Chinese President Xi Jinping and Japanese Prime Minister Shinzo Abe acknowledged the need for improved ties. Despite the diplomatic gesture, though, relations remain strained. Next year marks the 45th anniversary of the normalization of diplomatic relations between Japan and the People’s Republic of China, but celebrants of that auspicious occasion may unfortunately find little reason to cheer.

The most immediate source of tension stems from a deepening confrontation in recent months over the Senkaku Islands in the East China Sea, which China claims as the Diaoyu. In October, China denounced Japanese fighter aircraft for carrying out “dangerous tactics” in responding to Chinese surveillance aircraft operating near the disputed islands. A month earlier, Japan protested the presence of about 300 vessels and the incursion of two Chinese coast guard ships in the islands’ territorial waters. ...