The use of water cannons in sub-zero temperatures at Standing Rock is a political development of great consequence. They have not been used in the US since the civil rights movement in the 1960s.
It’s a matter of time before they will be reintroduced generally against protesters in the US since they are widely used in other countries. If we don’t stop their use in North Dakota in freezing weather, we’ll be fighting them in every major city.
A comparison would be the use of police in riot gear at peaceful demonstrations. Even during the civil rights movement police did not show up at protests in riot gear but were attired like regular police. Riot gear became a norm after the 1999 Seattle WTO protests & is something of a provocation.
There’s no reason for riot gear at protests most of which are peaceful & organized. The use of such aggression signals that long before Trump was elected those who run this country expected major opposition to their policies & attacks on civil liberties.