After border patrol officers lobbed 2-chlorobenzylidene malononitrile (CS), more commonly known as tear gas, at Central American migrants illegally trying to cross the border this Sunday near Tijuana, nearly every news agency in the country ran the same headline image — one depicting a woman with her two young children fleeing with a plume of white gas behind her. An odd article appeared in the Washington Post the following day bemoaning the deployment of illegal war gas.

Depending on interpretations, CS gas is illegal for use by troops in combat under the Chemical Weapons Convention. Granted, when I was deployed to Iraq we had CS gas out in the ammo bunker. CS gas is also in the Army’s DODIC, the catalog of all munition available to soldiers to request. Besides that, the article is strange in that on Sunday CS gas was not used by troops but rather by Border Patrol officers, members of a law enforcement agency. The skirmish on America’s southern border was not war, and the stipulations in the Chemical Weapons Convention don’t apply in this case. Many countries use CS gas to quell riots.

The bottom line here is that the Border Patrol’s use of CS gas was lawful. It was also far from unprecedented.

According to data researched by the Washington Times, CS gas was used about once a month at the border during the Obama administration: