Competitors like Russia and China are closing the advanced weapons gap with the United States, aiming to push the U.S. out of areas on their front doorstep.
Experts say they're improving their ability to target U.S. aircraft and ships, pushing the U.S. military farther away from potential conflict zones and constraining its ability to use force in regions such as the Baltic Sea and the South China Sea.
"Since the end of the Cold War, the U.S. military has never really had to fight an enemy that had its own arsenal of precision-guided weapons," said Mark Gunzinger, senior fellow at the Center for Strategic and Budgetary Assessments.
"It was able to use air bases and other bases located fairly close to the borders of an enemy because there wasn't that much of an air and missile threat to those bases,” he said. “That’s changing.”
Experts say Russia and China are improving their ballistic and cruise missile technologies and hoping to create what they call “anti-access area-denial bubbles” where they can threaten U.S. air and ground operations.
Russia is in particular presenting a challenge to the U.S. in the Baltics region, where it has recently been harassing U.S. aircraft and ships.
”You’ve seen some advanced air-to-air technologies that the Chinese and Russians are developing, not just in stealth technology, but in terms of the advanced aerodynamics, advanced air-to-air radars, advanced air-to-air weapons, advanced air-to-ground weapons," said Chris Harmer, senior naval analyst at the Institute for the Study of War.
Experts say Russia and China are also making inroads into the U.S.’ undersea dominance.
"Chinese nuclear attack submarines are just in absolute overdrive, how quick they're building and how fast the technology is developing,” Harmer said. "And we've seen a significant increase in Russian naval activity, Russian long-range naval activity, Russian ships conducting port calls to Bandar Abbas in Iran.”
Iran, too, is making progress, experts say.
“They still lack a precision in their offensive weapons, and they're still trying to obtain and develop more effective air missile defenses, but they're making progress and their weapons are getting more accurate and their capabilities are increasing in their range, as well as in their numbers,” Harmer said. “The Iranian navy is getting a lot bigger a lot quicker than anybody expected.”
To keep ahead of those advances, the Pentagon is focusing on developing high-end weapons systems that can avoid detection even in close quarters, like the B-21 long-range stealth bomber.
It is also seeking to develop the high-end capabilities of allies like the United Kingdom in order to extend its reach.
Deputy Defense Secretary Bob Work and British Defense Procurement Minister Philip Dunne earlier this month toured U.S. military bases where the two nations are working closely together on advanced weapons systems.
That includes the F-35 Joint Strike Fighter, a fifth-generation stealth fighter; the P-8 Poseidon, a maritime patrol aircraft designed to detect foreign submarines and ships; and the Trident Class II D5 missile, which deploy from U.S. and Royal Navy ballistic missile submarines.
"I wouldn't say that these are specific towards any countries, but they're against high-end capabilities," Work said. "Countries like Iran are buying the most advanced air defense systems in the world … Advanced air defense systems are proliferating around the world. Submarine technology is proliferating around the world. They're becoming quieter, hard to find."
Work said the U.S. and the U.K.’s 25-year defense plan released last year would allow the two nations to be "interoperable in these high-end fights."
"If we ever projected power around the globe and the U.K. government said, 'We're with you,' we'd be interoperable from the top to the bottom," he said.
Some experts say the U.S. is not spending enough on weapons research and development.
"At the same time, the Russians and the Chinese — the Chinese more so than the Russians — are spending an awful lot of money on research and development,” Harmer said.
And cyber theft, particularly by the Chinese, is a problem, they add.
“Today, we're capable of losing in 10 seconds via cybercrime 10 years worth of research and development,” Harmer said. "And especially for the Chinese that's been a big help to them in closing the gap.”
But they agree the main solution is fixing a wasteful and burdensome weapons buying system that can take decades to field a platform.
"The main issue for us is overcoming a very sclerotic system of acquisition," said defense analyst Norman Friedman. "It's not fast enough, and it's extremely poor judgment about the costs of programs, how much they should run, lack of ruthlessness ... an ability for someone at the top for many years to stand back and say, this is stupid."
Experts warn that in the meantime, competitors can make up in numbers what they can't make up in technology.
"As the Russians used to say during the Cold War, quantity has a quality all of its own," Harmer said. "Because the Chinese can put so much quantity into the water in a relatively small space and small time, they can more than overwhelm our technological advantage.”
Experts say they don't see any fixes to the shrinking technological gap anytime soon.
Defense Secretary Ash Carter, House Armed Services Committee Chairman Mac Thornberry (R-Texas) and Senate Armed Services Committee Chairman John McCainJohn Sidney McCainGOP senators appalled by 'ridiculous' House infighting MSNBC's Nicolle Wallace, Chris Christie battle over Fox News Trump's attacks on McConnell seen as prelude to 2024 White House bid MORE (R-Ariz.) have introduced reforms to fix the acquisition system, but experts say it’s too early to tell if their reforms are working.
“I find it worrisome that we can't seem to fix the procurement system but many very hard working people have tried,” Friedman said. “I mourn for what I see.”
Harmer added: “The Department of Defense would like to move faster. Of course, change is hard. Change is slow.”