Hidden in the article is why-They were used to disperse the demonstrations held every Friday in the village of Nebi Salah, between Salafiya and Ramallah, which end(ed) with participants hurling rocks at the soldiers and at vehicles plying the road to the settlement of Neve Tzuf. Throwing stones at soldiers and at innocent civilians caused the gas to be used. We can asume that if the demostration had been peaceful than measures would not have been taken.
Military campaign against ISIS must be accelerated, says U.S. to allies (Reuters)
from the article: IDF resumes use of prohibited tear gas canisters