Anti-ship ballistic and cruise missiles—latter-day counterparts to cannon fired from land—replicate this dynamic from the age of close-range gunnery. What should the Navy do about it? It's unclear whether the DF-100 is a cruise or ballistic missile. The “DF” nomenclature seems to indicate it flies a ballistic trajectory, while Jane's depicts the bird as a supersonic cruise missile. It may straddle the difference between ballistic and sea-skimming missiles, arcing high into the atmosphere but following a flatter trajectory than a ballistic missile. It would come at U.S. Navy task forces from yet another axis, augmenting anti-ship cruise and ballistic missiles and undersea munitions such as torpedoes or sea mines. Whatever the case, the new anti-ship missile purportedly reaches hypersonic velocity, meaning five or more times the speed of sound, during at least part of its flight. That boosts its chances of getting through U.S. Navy defenses. Defenders would have little time tor more than snap shots.