Okay I will subtract that point. However, selective reading through wikipedia, chemical warfare has been around for centuries...however...the first time it was used in a modern sense. ie. in a projectile weapon was by americans
http://en.wikipedia.org/wiki/Chemica...re#Rediscovery
"Later, during the American Civil War, New York school teacher John Doughty proposed the offensive use of chlorine gas, delivered by filling a 10 inch (254 millimeter) artillery shell with 2 to 3 quarts (2 to 3 liters) of liquid chlorine, which could produce many cubic feet (a few cubic meters) of chlorine gas. Doughty’s plan was apparently never acted on, as it was probably presented to Brigadier General James Wolfe Ripley, Chief of Ordnance, who was described as being congenitally immune to new ideas.
A general concern over the use of poison gas manifested itself in 1899 at the Hague Conference with a proposal prohibiting shells filled with asphyxiating gas. The proposal was passed, despite a single dissenting vote from the United States. The American representative, Navy Captain Alfred Thayer Mahan, justified voting against the measure on the grounds that "the inventiveness of Americans should not be restricted in the development of new weapons."
Obv. you will read through this and see that it has been used or proposed many times and i have selectively choosen this section to forward my claim. But i think when i was refering to as US or We i was meaning america in a gerneral sense was perhaps one of the first/perhaps second along side nazi germany. to begin actively researching and stock piling chemical warfare agents.