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.
Spc. Rawad Madanat/U.S. Navy
The U.S. military is developing the Boeing KC-46 refueling tanker to replace the aging KC-135 fleet now in use.
The KC-46A Pegasus is designed to carry passengers, cargo and injured military personal and can "detect, avoid, defeat and survive threats using multiple layers of protection, which will enable it to operate safely in medium-threat environments," according to Boeing.
The new KC-46A completed a successful first flight in September 2015, but the program has been criticized for schedule delays and cost overruns since the contract was awarded in 2011.
Boeing plans to build 179 KC-46 aircraft for the U.S. Air Force.
Amid criticism over schedule delays and cost overruns, several lawmakers have pledged to keep the program on track to deliver the planned amount of planes.
Above, the Pegasus tanker deploys its centerline boom for the first time, on October 9, 2015. The boom is the fastest way to refuel aircraft, at 1,200 gallons per minute.