Facing a growing threat from China, the Navy envisions drone ships keeping an electronic eye on enemy forces across the vast Pacific Ocean, extending the reach of firepower, and keeping sailors out of harm's way. The Navy is speeding development of those robotic ships as an affordable way to keep pace with China's growing fleet while vowing not to repeat costly shipbuilding blunders from recent years. The four largest drone ships are being used together this summer during a multination naval exercise in the Pacific Ocean.