Shared U.S.-Indian concerns over China's aggressive expansionism led Modi to join the "Quad" partnership alongside the U.S., Australia, and Japan. Benefiting from military export relaxations introduced by the Trump administration, India is also increasing its purchase of U.S. arms and related equipment. Yet even as this cooperation might seem like proof positive of a budding U.S.-Indian alliance, other factors undermine that consideration. For a start, India fails the reciprocity test when it comes to supporting U.S. security concerns. The Pentagon has not responded to my query as to whether the U.S. military attachés in New Delhi are to be afforded...