The U.S. Marines' version of the F-35 Joint Strike Fighter was declared ready for combat this year, but the Navy and Air Force are still waiting for the finishing touches to be made on their jets.
 
The fighter jet has been in development for nearly 15 years and is touted as the most advanced weapons system of the modern era, combining stealth capabilities, supersonic speed, extreme agility and state-of-the-art sensor fusion technology.
 
The price tag for all these benefits, however, is nearly $400 billion, making the program the most expensive weapons system in world history. To maintain and operate the JSF program over the course of its lifetime, the Pentagon will invest nearly $1 trillion, according to the Government Accountability Office.
 
The Pentagon is scheduled to purchase 2,443 F-35s, but criticism over the affordability of the program has prompted several lawmakers to reaffirm their desire to purchase the full order of aircraft.