Kinzhals are just air launched Iskander short ranged ballistic missiles. Russia calling them hypersonic weapons is technically accurate but misleading, as when people refer to hypersonic weapons they typically refer to weapons capable of sustained and maneuverable hypersonic flight within the atmosphere.<p>Patriot PAC-3 interceptors are literally designed to shoot down SRBMs, it's a primary use case. Many fundamental aspects of their design such as using (pseudo) hit-to-kill interception instead of a more normal blast fragmentation warhead are consequences of this focus. It's not surprising that this happened once Ukraine got modern Patriots.