WASHINGTON — The B-21 Raider stealth bomber is carrying out test flights at Edwards Air Force Base in California, the U.S. Air Force has confirmed.

The B-21 flew on Wednesday, Air Force spokeswoman Ann Stefanek said in an email. It was not the first time the Northrop Grumman-made bomber flew since its arrival at Edwards in November 2023, but Stefanek declined to say how many flights it has taken or provide other details, citing operational security reasons.

“Flight testing is a critical step in the test campaign managed by the Air Force Test Center and 412th Test Wing’s B-21 combined test force to provide survivable, long-range, penetrating strike capabilities to deter aggression and strategic attacks against the United States, allies and partners,” Stefanek said.

While the B-21 was unveiled with much fanfare in a December 2022 rollout at Air Force Plant 42 in Palmdale, California, the service and Northrop Grumman have since become more reticent about new developments in the highly classified bomber’s evolution. The War Zone first reported the B-21′s Jan. 17 flight.

Photographs of the B-21 have shown its nickname Cerberus — the multi-headed hound that guards the gates of Hades in Greek mythology — stenciled on its landing gear door.

After its Nov. 10 flight to Edwards, the B-21 moved into the flight testing phase, which includes taxiing, ground tests and flying operations.

Northrop Grumman has built or is in the process of building at least six test B-21s, including this first bomber. The B-21 program is now in the engineering and manufacturing development phase, and the test aircraft are production-representative platforms, meaning they are being built on the same line with the same tools, technicians and processes as production bombers.

Ellsworth Air Force Base in South Dakota is to be the first base to receive a Raider, scheduled for delivery in the mid-2020s.

The Air Force plans to have a fleet of at least 100 B-21s, which will replace the aging B-1B Lancer and B-2 Spirit bombers as they retire in the 2030s. The B-21 is meant to conduct penetrating deep-strike missions against adversaries with advanced radars and air defense systems. The aircraft can carry both conventional and nuclear weapons.

Each B-21 is expected to have an average procurement cost of $692 million, and the program has a price tag of $203 billion over 30 years.

Test pilots told reporters at the B-21′s December 2022 rollout that a flight test program like the one planned for the B-21 will be a “massive undertaking.”

Northrop Grumman B-21 test pilot Chris Moss said at the time that pilots will be watching to ensure the Raider flies as expected, experience how it feels and confirm its systems work as intended. The bomber will record data that is transmitted to the ground for analysis, he added.