Ish. There seems to be some vocabulary fuckery going on around the term "orbital", most likely due to a poor choice of wording upstream. "Orbital" in the shit-blew-up-outside-the-atmosphere sense EMP strikes are absolutely phase 1A of any large scale nuclear attack and such capabilities are trivially executed by ICBMs with appropriate warhead selection and detonation altitude parameters. "Orbital" in the EMP-weapons-literally-orbiting-the-planet sense violates several international treaties. Given the levels of secrecy required to pull that off for any length of time it seems unlikely but is impossible to rule out entirely.