The defense chiefs of Japan, Britain, and Italy on Saturday agreed to accelerate their planned joint development of a next-generation fighter jet, Japanese officials said. Meeting in Naples, southern Italy, the three ministers also confirmed that the public and private sectors will conclude their first contract as early as next year toward the goal of deploying the plane by 2035, according to Japan’s Defense Ministry. Japanese Defense Minister Gen Nakatani and his British and Italian counterparts, John Healey and Guido Crosetto, met on the sidelines of the Group of Seven industrialized nations…