I’d suggest the purpose is twofold:
1. To desensitise the public to the presence of military on and over the streets of urban areas.
2. To desensitize the troops to discharging their weapons in urban areas in the presence of unaware and unarmed citizens (subjects).
All part of preparing for marshall law and civil war.
Watch the video. See what they have planned for us. Full participation of the military within the US against civilian targets.