The rest of the world was watching the pomp, circumstance and speeches celebrating China’s 70th anniversary Tuesday, but military analysts were glued to another spectacle in the heart of Beijing: the arsenal of cutting-edge weaponry capable of challenging U.S. military might for decades to come. The lavish event marking seven decades of Communist Party rule gave Beijing a golden opportunity to showcase new hypersonic missiles, top-of-the-line drones, tanks, stealth bombers, unmanned underwater vehicles, helicopters that rival U.S. Black Hawks, and a host of other military technology that highlights the nation’s ever-rising defense budget and its long-term plan to cut into...