Dakota Pipeline protest on Twitter. Why does Obama not use tear gas and water canons on anti-Trump rioters?

Why does Obama not use tear gas and water canons on anti-Trump rioters? Obama urges anti-Trump rioters to keep up the good work.

Law enforcement officers surround demonstrators protesting against plans to pass the Dakota Access pipeline during a standoff at the Backwater Bridge in Morton County, North Dakota, U.S., November 20, 2016. © Morton County Sheriff's Department / Handout via Reuters...https://www.rt.com/usa/367592-dapl-protest-bridge-teargas/

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