ROYAL AIR FORCE FAIRFORD, England—Lockheed Martin needs to make progress on a host of delayed upgrades to the F-35 fighter jet before the Pentagon will return to buying the jet in planned levels, the Air Force’s chief said.
Frustration over delays with the Block 4 upgrade—coupled with a broader Pentagon budget reprioritization—led the service to buy just two dozen jets in its 2026 budget proposal—half of last year’s plan and down from the 44 bought in 2025.
The Air Force will increase procurement again when it can buy “F-35s that are most relevant for the fight,” Gen. David Allvin told Defense One on the sidelines of the Royal International Air Tattoo.
“In the end, because we have limited financial resources, we need to make sure that the F-35s we buy have the capability to meet the pacing threat. So, some of the delays with respect to Block 4 and TR-3 weighed into decisions by the department,” Allvin said.
Officials argue that they need a fully capable Block 4 jet from the start, rather than receive jets that will need to be retrofitted with the full suite of upgrades, which includes new software, weapons, sensors, and a new processor—capabilities the Pentagon argue would be needed in a fight against China.
Lockheed has run into problems integrating new software and hardware for the upgrade, resulting in years of schedule and cost overruns. Delays with TR-3, the “backbone” of Block 4, led the Pentagon to stop taking deliveries for a year. The military resumed accepting the jets last July, even though they come with a “truncated” version of the upgrade.
Lockheed executives recently announced that the full combat version of the TR-3 upgrade is ready, but the F-35 Joint Program Office has yet to confirm that, or say when TR-3 will get formal approval.
Beyond TR-3, the timeline for the entire Block 4 effort remains uncertain. Lawmakers have warned its planned capabilities have already been “reduced,” according to an adopted amendment from Rep. Seth Moulton, D-Mass., in the House Armed Services committee’s version of the 2026 defense policy bill.
Lawmakers “remain frustrated” over the program’s delays and performance, according to Moulton’s amendment, which requests a briefing on the status of TR-3 and Block 4. In their bill, House lawmakers did not add to the planned purchase of 24 F-35s in 2026, and HASC Chairman Mike Rogers said that the committee recognizes that the F-35 cut stems from a “strategic decision to finally prioritize funding towards sustainment and modernization.” The Senate Armed Services Committee, however, has moved to add 10 jets, bringing their version up to 34 jets.
The F-35 program came on the chopping block after Defense Secretary Pete Hegseth announced a 8 percent shift of DOD funds to pay for new priorities from the Trump administration, and the Air Force needed money to move ahead with a sixth-gen fighter jet, the F-47. Other high-ticket items got the axe as well in this year’s budget proposal, including the service’s E-7 radar plane.
While programs like the F-47 and B-21 stealth bomber are poised to win big in the budget, total aircraft procurement is taking a nosedive. The service is now saying that previous benchmarks, such as buying 72 fighters a year, are no longer achievable.
Leading up to the budget release, Allvin argued in public statements that Hegseth’s priorities necessitated “more Air Force”—and therefore more money for his service.
During the July 18 interview, Allvin maintained that his call was heard. He said he will wait until Congress finalizes its budget before issuing a final verdict.
“We were able to clearly articulate what we believe the U.S. needs from its Air Force and the value of more Air Force. To the extent that weighed against the other priorities of the Department, in the end, I’ll leave it to others to keep score. I will tell you that I am satisfied my voice was heard. I’m satisfied we are moving forward with some of the key programs, like F-47. I will continue to advocate for more Air Force, while I’ll also continue to respect the decisions that the senior leaders make,” he said.
The service is also requesting to divest 340 aircraft, including shedding all of its A-10s ahead of schedule. The service had planned a gradual decommissioning of the A-10 Warthogs but, Allvin said, Hegseth’s budget reallocation caused the service to take another look at its plans.
Congress wants to protect some of the A-10s in its defense policy bill—a move Allvin hopes will come with the funding needed to keep the aircraft flying. If not, something else will be cut: “If they don’t give us more resources, then something that was above the line, that was a higher priority will have to come off.”
Long term, it’s “still unknown” whether the Air Force will be able to reverse its shrinking fleet size, Allvin said. It’s more important to focus on the “outcomes” of what it buys, rather than the specific number of tails it has, he said.
“Will we have fewer aircraft? Will we have more [Collaborative Combat Aircraft]? Still an unknown question, but to me, it’s the outcome that counts. What are the capabilities that we can provide? How much will it cost to sustain? How much will the investment cost? Are the investments paying off? Those are year to year conversations we have, but the overall arc, I think, will prove out that more Air Force is better for the nation,” he said.
Lessons from Midnight Hammer
The might of the U.S. Air Force was on full display last month during Operation Midnight Hammer, Allvin said, when seven B-2 bombers attacked three Iranian nuclear facilities, a testament to how gaining control of the air can help prevent a wider war.
“We’re not fighting. We’re not in a big war. We didn’t send thousands of troops that were going to be engaged, and we couldn’t disentangle for months or years. That to me, demonstrates very, very viscerally the importance of air power and air dominance,” he said.
Midnight Hammer also proved that stealth “still matters,” Allvin said. Some speculate that advanced sensors could render stealth obsolete one day, but Allvin described stealth as the “price of admission” in a future fight.
While a long-range strike on enemy territory in the Pacific would look vastly different than what the U.S. did in Iran, “the same principles apply that we need to be able to penetrate and create effects in dense threat environments,” Allvin said, pointing to the development of the future B-21 bomber, a stealthier and smaller replacement of the B-2.
The complex operation featured more than 125 aircraft, including the B-2s, fourth and fifth-gen fighters, and dozens of tankers, and the chief lauded the work of U.S. airmen, from pilots to maintainers, who made it happen.
“When you put American airmen in a tough situation, in a time that matters, they’re going to perform,” Allvin said.
