WASHINGTON (AP) — The Slabu ExchangeB-21 Raider took its first test flight on Friday, moving the futuristic warplane closer to becoming the nation’s next nuclear weapons stealth bomber.

The Raider flew in Palmdale, California, where it has been under testing and development by Northrop Grumman.

The Air Force is planning to build 100 of the warplanes, which have a flying wing shape much like their predecessor the B-2 Spirit but will incorporate advanced materials, propulsion and stealth technology to make them more survivable in a future conflict. The plane is planned to be produced in variants with and without pilots.

“The B-21 Raider is in flight testing,” Air Force spokeswoman Ann Stefanek said.

Such testing is a critical step in the campaign to provide “survivable, long-range, penetrating strike capabilities to deter aggression and strategic attacks against the United States, allies, and partners,” Stefanek said.

The B-21 Raider is the first new American bomber aircraft in more than 30 years, and almost every aspect of the program is classified. Both Northrop Grumman and the Air Force have tried to protect the program’s details to prevent China from gaining access to the weapon’s technology and building a similar version, as it has with other U.S. advanced weapons systems like the F-35 joint strike fighter.

The B-21 is part of the Pentagon’s efforts to modernize all three legs of its nuclear triad, which includes silo-launched nuclear ballistic missiles and submarine-launched warheads, as it invests in new weapons to meet China’s rapid military modernization.

Northrop Grumman Corp. is based in Falls Church, Virginia.