Well before Operation Desert Storm or the U.N. inspections that followed it, Iraq had already begun to build chemical weapons. After launching a research effort in the 1970s, Iraq was able to use chemical weapons in its war against Iran and to kill large numbers of its own Kurdish population in the 1980s. On June 28, 1987 in Sardasht, on two separate attacks against four residential areas, victims were estimated as 10 civilians dead and 650 civilians injured. Iraq massively used chemical weapons during Iran–Iraq War, and so far, Kurdish people are the biggest victims of chemical weapons. Iraq used mustard gas in an attack against Kurdish people on March 16, 1988, Halabja chemical attack. The attack killed between 3,200 and 5,000 people and injured 7,000 to 10,000 more, most of them civilians. During Iraqi chemical attacks against Iran, many Iranian military forces were killed by nerve agents. At the time, the attacks were actively supported by the United States.