But any number of non State actors would. The IRA or ISIS or Hezzbollah for example. They probably don't have the tech capabilities to RE their own GPS firmware, but non-orbiting rocket science isn't that hard. Iron Dome does okay against simple rockets, but a big guided rocket (V2 size) would be a different problem entirely.

Obviously drone attacks make use of GPS, and it's a worry to many -- for example, there is frequently GPS jamming when Putin is visiting somewhere.