Check out the latest from the Air Show China. This year, China is showcasing numerous models of unmanned aerial vehicles (drones); most of which are for sale. Look closely at the WJ600 model: "The Chinese drone of greatest potential concern to the U.S. is the one with several missiles and a jet engine—called the WJ600—which was displayed by China Aerospace Science & Industry Corp., or Casic, one of China's top weapons makers. Casic officials declined to comment, but a video and a two-dimensional display by the company showed Chinese forces using the WJ600 to help attack what appeared to be...