By MARI YAMAGUCHI
ENIWA, Japan (AP) — Japan has been building up its defenses to counter strategic threats, but its arms industry is struggling both on the home front and overseas. The country’s Self Defense Force needs the more advanced aircraft and weaponry of U.S. arms manufacturers as it faces incursions by Chinese fighter jets and naval vessels and North Korean missile launches. So its big defense manufacturers like Mitsubishi, IHI Corp. and Kawasaki Heavy Industries are fighting to sell 20th century tanks, aircraft and warships at a time when Japan’s military is in the market for unmanned aircraft like Tritons made by Northrop Grumman and Boeing’s undersea Echo Voyager. Overseas sales are also lagging, raising worries that the industry has a bleak future.