I can fully understand why you believe that to be true, but the thing is there has not yet been a situation in this country where law enforcement and/or military personnel have been commanded to do so. Although some would say that there have been incidents in the history of race relations involving blacks and native Americans, and also incidents during times of war that are at odds with your contention.
Incidents long ago here in America and Indian issues were not against US citizens.
The world has cases where it is usual for troops to be used that way but federal law prohibits here and troops swear an oath to the constitution, not a person or political movement.
If you truly feel troops will follow orders to shoot citizens the you best not be thanking them for their service as they are an enemy to the republic and you.
Please note: My reply was unintentionally blunt.