America’s newest nuclear stealth bomber is made its public debut after years of secret development and as part of the Pentagon’s answer to rising concerns over a future conflict with China.

The B-21 Raider is the first new American bomber aircraft in more than 30 years. Almost every aspect of the programme is classified. Ahead of its unveiling at an air force facility in Palmdale, California, only artists’ renderings of the warplane have been released. Those few images reveal that the Raider resembles the black nuclear stealth bomber it will eventually replace, the B-2 Spirit.

The bomber is part of the Pentagon’s efforts to modernise all three legs of its nuclear triad, which includes silo-launched nuclear ballistic missiles and submarine-launched warheads, as it shifts from the counterterrorism campaigns of recent decades to meet China’s rapid military modernisation.

China is on track to have 1,500 nuclear weapons by 2035, and its gains in hypersonics, cyber warfare, space capabilities and other areas present “the most consequential and systemic challenge to US national security and the free and open international system”, the Pentagon said this week in its annual China report.

”We needed a new bomber for the 21st Century that would allow us to take on much more complicated threats, like the threats that we fear we would one day face from China, Russia, ” said Deborah Lee James, the air force secretary when the Raider contract was announced in 2015. “The B-21 is more survivable and can take on these much more difficult threats.”

While the Raider may resemble the B-2, once you get inside, the similarities stop, said Kathy Warden, chief executive of Northrop Grumman Corp., which is building the Raider. “The way it operates internally is extremely advanced compared to the B-2 because the technology has evolved so much in terms of the computing capability that we can now embed in the software of the B-21,” Warden said.

Other changes likely include advanced materials used in coatings to make the bomber harder to detect, new ways to control electronic emissions, so the bomber could spoof adversary radars and disguise itself.