The Pentagon estimates the total price tag for Boeing's F-15EX fighter aircraft program is $12.5 billion, a sum that allows the Air Force to replace its oldest two-seater fighters with a modernized variant of the 1970s-design combat system and puts a significant six-year squeeze on available funding to buy F-35 aircraft as Lockheed Martin struggles to reach objective manufacturing rates. The Defense Department -- which proposed launching the F-15EX in fiscal year 2020 with a $1 billion, eight-aircraft buy --...