Some technologies, like precision-guided weapons, represent breakthroughs based on existing science. China, for instance, is developing advanced anti-ship ballistic missiles capable of destroying aircraft carriers. Others are entirely novel concepts, such as the EXACTO self-steering bullet developed by the U.S. Defense Advanced Research Projects Agency (DARPA) in 2015. As China, Russia, the U.S., and other nations invest heavily in military modernization, a new era of high-tech arms competition is unfolding.