The US Air Force just offered a fresh look at its new B-21 stealth bomber

• New photos show the ongoing testing of the US Air Force's B-21 Raider stealth bomber.
• The B-21 is expected to replace legacy bombers and offers several major modernization upgrades.
• Aerial refueling is a part of the testing process for the aircraft, which will be delivered next year.

The US Air Force released new photos of its B-21 Raider stealth bomber as the service continues flight testing of the aircraft intended to be the backbone of the force's long-range strike capabilities.

The B-21, developed by Northrop Grumman, is the Air Force's next-generation strategic bomber and a cornerstone of the service's nuclear modernization efforts, alongside the Sentinel intercontinental ballistic missile. The program remains on schedule and within budget, with production now accelerating ahead of planned deliveries of production models next year.

One of the new Air Force photos of the B-21 Raider released on Tuesday shows the bomber being refueled by a KC-135 Stratotanker and, as military news outlet The War Zone first noticed, offers the first full overhead view of the aircraft, including its refueling receptacle, paint markings, and exhaust.

The aerial refueling, the service said, represented "rapid maturation of the weapon system." Aerial in-flight refueling for aircraft like the B-21, which its manufacturer calls "the most fuel-efficient bomber ever built," is critical in a potential conflict, enabling the fleet to stay in the air longer, dramatically extending reach.

Aerial refueling tankers, for instance, have enabled US B-2 Spirit stealth bomber operations against Iran.

That said, the B-21, slated to eventually replace the Air Force's B-1 Lancer and B-2 Spirit bombers, has been designed for fuel efficiency, consuming a fraction of the fuel of some legacy aircraft.

"This long-range strike bomber will reduce the demand on our tanker fleet and free up assets to support the joint force," Air Force Chief of Staff Gen. Ken Wilsbach said in a service statement on the recent testing work. "This will provide a wider range of employment options and the deterrence our nation requires."

The Air Force and Pentagon have both viewed the B-21's development and testing timeline as successes, with flight tests and early procurement remaining on schedule.

The Air Force is now accelerating the production of its new bombers and expects to procure around 100 by the mid-2030s, although there have been calls to increase procurement. Airpower experts have advocated for a much larger fleet, arguing its necessity to effectively counter China.

"The B-21 program is the leading edge of the acquisition mindset we are instilling across the force," said Air Force Gen. Dale White, the Pentagon's direct reporting portfolio manager for critical major weapon systems. "Every test proves the success of empowering our leaders to deliver integrated capability from the start."

The Air Force is continuing to test the B-21 at Edwards Air Force Base in California. Other bases like Ellsworth, Whiteman, and Dyess will eventually house the B-21 for training and main operations. It'll mark its first operational fielding next year at Ellsworth.

Both the Air Force and Northrop Grumman have said that the Raider represents a major jump in bomber capability, including next-generation stealth, software, and weaponry.

The aircraft also features an open system architecture, meaning it can be quickly and easily upgraded with new technologies without needing to build a completely new version.