Commentary Missile defense is not only a reality in the Indo-Pacific but also a necessity. Nearly every country in the region is acquiring some kind of capability to blunt the threat from a proliferating number and variety of ballistic, cruise, and even hypersonic missiles. The next step—and one where the United States should take the lead—is to get like-minded states to cooperate in building a common shield against a shared missile threat. The threat is self-apparent. North Korea has moved from short- and medium-range missiles that mostly threatened South Korea and Japan, to developing intercontinental ballistic missiles (ICBMs) that could target the U.S. mainland. North Korea’s recent testing of a submarine-launched ballistic missile (SLBM) only compounds an already tense situation. China, however, constitutes the greatest missile threat, not only to the United States and its Asian allies—particularly Japan and Taiwan—but even to farther-away states like Australia. China has long deployed …