Armed drones repeatedly kill unarmed civilians, either by mistake or as collateral damage. Multiple human rights organizations (ACLU, Human Rights Watch, and Amnesty International among them) as well as the United Nations have noted major concerns about the targeted drone strikes that have killed numerous civilians. The US claims that the families of the dead are given recompense but human rights organizations have not found this to be true.
If we wish to curb anti-American sentiments aboard, this is the place to begin. Killing civilians only breeds more hatred for America and thus empowers the terrorists forces seeking new recruits. End these sorts of foreign entanglements and we can reduce the number of those willing to attack Americans.