The marines have what they call Marine Expeditionary Unit Special Operations Capable. They are not officially part of SOCOM but there are Marine Officers who worked in these units working a SOCOM HQs these days. I helped train one marine infantry reserve unit that turned itself into a Tactical PSYOP, Civil Affairs unit. I think that units like these will eventualy be added to SOCOM if the Marines want to be part of the puzzle palace LOL.