tokyo japan delay decision develop new advance fighter jet four source say military planners struggle settle design officials splash new u.s. equipment ballistic missile interceptors f-35 stealth plan face grow military threat north korea increase activity chinese air force jet east china sea japan pressure improve defenses two front delay new fighter know f-3 raise question mark future could one world lucrative upcoming military contract estimate 40 billion develop deploy decision first half 2018 would late include core program new five-year defense equipment plan begin april 2019 japan reveal end next year direction f-3 decision put back say one source knowledge discussion people speak reuters ask identify authorize talk media say decision whether forge ahead domestic program seek international collaboration would likely come 2018. regard f-3 decision include whether delay choice come conclusion spokeswoman ministry defence acquisition technology logistics agency say analysts estimate develop f-3 could cost 40 billion figure describe another source initial cost defense budget around 50 billion increase past years annual percent outlay even spread years development represent major undertake would come time japan spend record amount u.s. equipment include lockheed martin corp f-35 jet raytheon defense missiles boeing co textron inc tilt-rotor osprey troop aircraft 2013 japan procure 118 billion yen billion equipment u.s. government foreign military sales fms system last year outlay quadruple 486 billion yen president donald trump tokyo last week call prime minister shinzo abe purchase additional u.s.-made weapons administration push washington ally contribute joint defense defense focus counter threat pose north korean ballistic missiles nuclear weapons japan defense force however want f-3 counter grow chinese air power sky western pacific east china sea tokyo beijing lock territorial dispute japanese fighters scramble record 806 time intercept chinese plan year end march 31. second role yet-to-be-built fighter reinforce japan defense industry give mitsubishi heavy industries mhi suppliers first fighter jet program since japan build f-2 fighter two decades ago mitsubishi heavy maker world war two-era zero fighter january 2016 test prototype jet atd-x develop around 350 million see first step toward new homegrown frontline stealth fighter support domestic-only program strong among government officials bureaucrats worry potentially enormous expense develop components scratch support international collaboration share cost overseas partner tap technology fly box without systems constitute fighter weapons sensors say another source possible overseas partner include bae systems lead designer high-altitude eurofighter interceptor back british government f-35 builder lockheed martin boeing maker f-18 strike fighter respond initial request information ministry defence oversee f-3 plan exclusive japan delay multi-billion dollar fighter jet development source