Key refueling-related tests for the B-21 Raider are now underway, an Air Force spokesperson confirmed to Defense One, the latest milestone towards delivering the next-generation bomber by 2027.
On Tuesday, several open-source intelligence accounts and plane spotters posted images of a B-21 approaching a KC-135 tanker over California. One account cited flight radar data indicating that the tanker was from Edward Air Force Base’s 370th Flight Test Squadron. Other photographs and videos showed the bomber being followed by an F-16 fighter jet.
“We can confirm that a B-21 Raider flight test aircraft completed a test event involving a close-proximity flight with a KC-135 Stratotanker,” the spokesperson said in an emailed statement. “This flight is part of the ongoing, rigorous test campaign to validate the B-21’s capabilities and operational readiness.”
The B-21’s latest appearance comes as President Trump’s war in Iran stretches into its second week and the U.S. Air Force’s current long-range bomber fleet continues to hit Iranian missile sites and other military infrastructure. The first Raider is scheduled to be delivered next year, but some defense experts said the program’s recent progress might mean key milestones will be hit sooner than anticipated.
“It’s a great sign that, once again, what we’ve been hearing now for a few years is the program is on track and on time, maybe even ahead of schedule,” said Mark Gunzinger, the Mitchell Institute’s director of future concepts and capability assessments.
Gunzinger, a former B-52 bomber pilot, said the close approach of a B-21 to a tanker is a key preliminary step.
“When you have a new aircraft, you do proximity testing, you approach the refueling envelope, and you do that multiple times.” Gunzinger said. “You practice emergency breakaways from a tanker, which is a standard training event for all aircrew before you actually come in contact. So, that will likely progress until it’s actually hooking up and unhooking, hooking up and so forth. And then they actually will pass fuel.”
Last month, the service reached a deal with Northrop Grumman to accelerate B-21 bomber production by 25 percent, using $4.5 billion approved for the effort in the 2025 reconciliation spending bill.
While the original plan was to spend that funding over five years, the Defense Department plans to allocate it all by October “if that can be done without sacrificing effectiveness,” a Pentagon planning document obtained by Defense One last month said.
Air Force officials said the service remains “on track” to deliver the first B-21 Raider in 2027 to Ellsworth Air Force Base, South Dakota, which will serve as the bomber’s first main operating base and formal training unit.
New tanker?
While the service prepares for a new bomber, a timeline for a new refueling tanker is less clear. The KC-135, seen refueling the B-21 by plane spotters, has been in service since the late 1950s. Last year, the Air Force weighed keeping the tanker in service past its originally planned 2050 retirement date.
Lt. Gen. Reba Sonkiss, the interim head of Air Mobility Command, told reporters last month that the service needs to seriously discuss what the future replacement for its aging tankers will be, given that they’ll be supporting next-generation airframes like the B-21.
“I cannot have a 90-year-old tanker refueling a B-21, and if you do the math, as we reach the end of programs for things, that’s the reality,” Sonkiss said during a Feb. 24 roundtable at the Air and Space Force Association’s Warfare Symposium.
Gunzinger said the KC-135 is capable of refueling a B-21, but agreed with Sonkiss’ point. The 1950s-era tanker was built with other conflicts in mind, and it needs key upgrades to stay relevant in a fight against a future adversary.
“I think that’s a valid point. The Air Force’s Global Strike Forces were designed to operate together back in the 50s and in the 60s,” Gunzinger said. “My point is KC-135 [was] never designed to be part of a secure communications network of the kind that you would want to operate in a conflict with China.”
