Sounds like a planned mass violation of Posse Comitatas.
The Marines have been doing this for 2 decades when the MEUSOC program was initiated. They use U.S. cities because the infrastructure cannot be replicated on base for the planning and operations. Furthermore, the Norfolk/Virginia beach; Oceanside, CA; and Jacksonville, NC areas are not typically used because of the troops' familiarity with those areas. The idea is to get them in an area where they are not familiar with. I've been in many of these operations, and it was always about development to carry out 17 specific missions overseas, in a challenging environment.
This isn't that hard to verify. Ask any Marine who has been on a MEUSOC deployment, particularly the "Maritime Special Purpose Force (MSPF); but not exclusively limted to that group. Everyone on the ship knows the deal. It's routine.
What is law enforcement involvement? To intervene if a citizen "rolls up" the recon (which has happened). Civilians tend to wig out when a group of young men with long guns and other gear accidentally get exposed.
There's nothing to see here. Concentrate on your local and state efforts dealing with constitutional protections.