The US is upgrading its fighter fleets in Japan, boosting its Pacific airpower with the newest jets

• The US is revamping the aircraft at its bases in Japan, the Pentagon announced.
• Dozens of F-35s will replace older aircraft, marking a significant upgrade.
• The boost comes as the US reassesses how its airpower would fare in a conflict with China.

US airpower in the Pacific is about to get a major upgrade, as the Pentagon announced it will be replacing aircraft at some bases in Japan with dozens of F-35 stealth fighters.

The move comes as the US looks at the lethality and survivability of its Pacific aircraft and airfields in a potential conflict with China.

The US Department of Defense released information on its new modernization plan for aircraft based in Japan on Wednesday, noting that the effort will take several years and reflect "over $10 billion of capability investments to enhance the US-Japan alliance, bolster regional deterrence, and strengthen peace and stability in the Indo-Pacific region."

As part of the plan, the Air Force will replace almost 50 F-15Cs and F-15Ds at Kadena Air Base with 36 F-15EX Eagle II strike fighters. And at Marine Corps Air Station Iwakuni, the number of F-35Bs jump jets — capable of takeoffs from short runways and amphibious assault ships — will be "modified" to further support the US' modernization plan, the press release said.

Perhaps most notably, the US Air Force's presence at Misawa Air Base is getting revamped with 48 F-35A stealth fighters replacing the current 36 F-16 Fighting Falcon multirole fighters, "leading to greater tactical aircraft capacity and capability," the release added.

Such a move would be a jump forward for the US' airpower in Japan, bringing fifth-generation fighter jets to bases directly in the line of potential conflict with China, adding to the capabilities of the F-22 Raptor fleet at Kadena.

It also signals, as the Pentagon's release said, "The Department's plan to station the Joint Force's most advanced tactical aircraft in Japan demonstrates the ironclad US commitment to the defense of Japan and both countries' shared vision of a free and open Indo-Pacific region."

It's the most recent sign of how the US and Japan are working together to deter a clash with China.

Back in May, DoD announced the two were jointly developing a defense system to counter hypersonic missiles, which are thought to be nearly impossible for current missile-defense systems to defeat. China, as well as Russia, boast hypersonic missiles in their arsenals; the US is currently working on one of its own.

The US is also working on shoring up its bases in the Pacific against a potential Chinese missile strike, which could feature a massive bombardment that renders US and Japanese aircraft, airfields, and command and control centers useless.

A recent Congressional letter to the Air Force and Navy's top leaders said the US isn't doing enough to protect its Pacific forces from such an attack. Back in May, 13 members of Congress pointed out glaring vulnerabilities in the Pacific, demanding immediate changes.

"With its current strike capabilities," the lawmakers wrote, "China can attack all US bases in the region, targeting US service members from Okinawa to those on US territories of Guam and the Commonwealth of the Northern Mariana Islands."