The Cambridge thug department said it had no military weapons. City councilors demanded a full inventory, and discovered it had 64 military assault weapons.
The M4 assault rifle is not merely "military-style." It is a smaller, newer variant of the M16, and the US Army is moving to it.
As for the armored vehicle, indeed it is not a "tank". A tank, by definition, has a cannon. Nonetheless, it may mount other weapons. I doubt that Cambridge has ever had an event for which it needed an armed and armored vehicle, and if it ever did, surely Cambridge could ask for help from Boston. The bridges to Boston are just a few hundred meters long.
Every city should force its thug department to furnish an inventory. Don't be distracted by the question of "What weapons do you get?" The main question is, "What weapons do you have?"