AT DAWN ON November 21st the Russian missiles slammed into the central Ukrainian city of Dnipro. Some were Kh-101 cruise missiles, carried by hulking Russian bombers. Others were Kinzhal ballistic missiles, fired from Russian jets. And at least one was new and nameless. Videos showed six warheads descending, almost vertically, onto the city, each releasing a slug of smaller projectiles. What was this mysterious weapon?