When the United States carried out a successful test recently of an advanced high-speed, long-range weapon ostensibly designed to reduce U.S. reliance on nuclear arms in a crisis, it set alarm bells ringing in China. Far from reassuring Beijing, the May 1 test of the sleek hypersonic unmanned aircraft, known as the X-51A WaveRider, has added to China's concerns that U.S. superiority in conventional weapons may make nuclear conflict more, not less, likely.

During the test, the WaveRider's scramjet engine ignited high above the Pacific Ocean, thrusting the demonstrator to a speed of nearly 6,245 kilometers per hour (KPH), just over five times the speed of sound. Scramjet stands for supersonic combustion ram jet, which has no moving parts. Fuel is mixed with air rushing into the combustion chamber and then ignited to provide power.

The WaveRider flew for 3½ minutes on scramjet power, the longest such flight in history. At that speed, a flight from New York to Los Angeles could take less than 39 minutes.