Only the President of the United States may authorize the use of riot control agents in war, even for defensive purposes, according to official U.S. military doctrine (pdf), although the Secretary of Defense may authorize their use for the protection or recovery of nuclear weapons.
So it was anomalous to say the least when employees of Blackwater Worldwide private security firm released a canister of CS gas over a Baghdad checkpoint in 2005, as reported by the New York Times today. See “2005 Use of Gas by Blackwater Leaves Questions,” by James Risen, January 10.
“A United States military spokesman in Baghdad refused to describe the current rules of engagement governing the use of riot control agents,” according to the Times story.
But to a great extent, those rules of engagement are specified in a U.S. Army Field manual which describes the permitted uses of riot control agents in wartime and in peacetime, as well as the authority required to employ them.
The 2003 Field Manual, which is still in effect, is FM 3-11.11, “Flame, Riot Control, and Herbicide Operations,” March 10, 2003.
The document has not been approved for public release, but a copy was obtained by Secrecy News. About 25 pages of the document, which detail the preparation of explosive devices, have been withheld from online publication by Secrecy News.
See, relatedly, “Blackwater Drops Tear Gas Grenades on Iraqis” by Jason Sigger, in Wired News’ Danger Room.