The Pentagon's answer to rising concerns over a future conflict with China is the public debut of America's newest nuclear stealth bomber. The B-21 Raider is the first new American bomber in more than three decades. The program is classified almost all the time. Artists' depictions of the warplane have been released ahead of Friday's unveil at an Air Force facility. The Raider is similar to the black nuclear stealth bomber, the B-2 Spirit. As it shifts from the counterterrorism campaigns of recent decades to meet China's rapid military modernization, the Pentagon is modernizing all three legs of its nuclear triad, which include silo-launched nuclear missiles and submarine-launched warheads. The Pentagon said this week that the most consequential and systemic challenge to U.S. national security and the free and open international system is China's progress in hypersonics, cyber warfare, space capabilities and other areas.