Pentagon officials say "countries of concern" such as China and Russia are close to having weapons that can compete with America's latest stealth fighter jets.
But experts in the field question the hundreds of billions of dollars the government has poured into programs it says are essential for America's security.
"We can't ignore the advancement in technologies that our major countries of concern have out there in the world today," Marine Corps Col. Kevin Killea tells U.S. News. The head of the Corps' Aviation Weapons Requirements branch says fifth-generation aircraft, such as the F-35B Lightning II, will be critical if the military wants to keep up on overseas threats in the next decade.
"If you're not fifth-generation, that's the ticket to play," he says. "That's the price of admission in that fight. If you don't have a capability that is at least equal to or better than them, you're not going to last very long."
"We need to evolve. Our enemy is evolving," adds Marine Gen. Matthew Glavy, assistant deputy commandant for Aviation. "It goes back to out-pacing and out-tempoing your enemy."
"You have to be paranoid. That's what we're paid to do," he adds.
The F-35 Joint Strike Fighter program is now considered the single most expensive weapons program in the history of the military. This is largely due to cost overruns spurred on by the military's desire to have one airplane with versions for the Marine Corps, Air Force and Navy – all of which have different requirements for a fighter.
Killea is excited by what the F-35 will bring to the Marine Corps as it continues a "rebalance to the Pacific."
"Forget about the fact that it's stealth," he says. "What this airplane is going to do is give incredible situational awareness to everybody on the ground, everybody flying other airplanes around it that are networked into it…and don't forget the ship it came from, and the forward arms and refueling points."
Killea uses the analogy of roadside radar detection to explain the kind of information a fifth-generation fighter can gather. A simple radar detector can just tell a driver there is a radar gun nearby. An advanced system would be able to determine where the radar detector is, how far away it is and how to evade it.
"It not only locates threat systems, it identifies them and tells the guy in the F-35 where not to go and where to go," he says.
This network of information could then be distributed to other aircraft such as the CH-53K Super Stallion, variants of the H-1 helicopter and the new MV-22 Osprey.
Killea points to China, Russia and India's focus on developing their own versions of a fifth-generation fighter.
"We have been pretty smart about the way we've adapted real time, but we've never lost sight…on not fighting the last fight and looking forward to what we need to do to be credible in the next fight," he says.
But one expert in Asian security says these concerns might be aimed at paper tigers.
Tom Snitch, a security consultant, used to be a senior advisor for nuclear and weapons control policy at the U.S. Arms Control and Disarmament Agency. He has spent much of the last 20 years studying the military assets of Russia and China, including seeing MiGs fighter jets "up close."
"It's hard for me to believe they are developing a capability that is costing us a billion dollars a plane to have the same attributes and capabilities," he tells U.S. News. "The Chinese and Russians are decades behind us in this technology."
The Marine version of the F-35, which includes a second engine to allow it to land vertically, will cost just under $240 million each, though the overall cost of developing the program exceeds $1 trillion, according to some estimates.
Snitch questions the kind of scenario in which the U.S. would get into a dogfight with another country.
And if the goal is simply to provide an intelligence hub, that could be provided more safely and cheaply with a network of drones or modifying existing fighters like the F-16.
"When you look at China, and that phantom stealth fighter they rolled out a year ago, that was some nifty construction," he says. "If we're having trouble with it, what do you think the Russians are dealing with? Or the Chinese?"
He does, however, see the validity in developing a weapon and broadcasting that it could defeat an opponent's version. The Reagan administration touted a plan to develop the futuristic Strategic Defense Initiative, or "Star Wars," to protect the U.S. from nuclear ballistic missiles more than 20 years ago.
"It was 'Listen, guys. Don't even think about it. Because if you do, by the time you get it done, we're going to have something better than you have,'" he says. "That's not an invalid argument, but a billion dollars apiece [for the F-35], are there less expensive solutions?"
"I'm not a critic of the F-35, but it seems to me that when you think about what it needs to do and who it needs to do it against, I don't think there are a lot of credible threats in the world that you couldn't do for less money, and without a pilot," he adds. "We're in a situation where dollars count. And what's the best use of a billion dollars?"