Wikileaks has a document up, stamped secret, that claims to be a two-year old set of US rules of engagement in Iraq. The big papers are all over it, because it appears to authorize raids into Syria and Iran. I'm intrigued by section 3.C.(3) Riot Control Measures, which includes the use of riot control agents -- tear gas, and the like.
It says that riot control agents can be used:
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