Weis unveiled the plan to equip and train the department's 13,500 officers with M4 carbines on Friday. Details about when the change would happen and who would pay for the guns were not disclosed.
The idea came as a surprise to many, since Chicago Mayor Richard Daley is a vocal gun control proponent. At a news conference Saturday, Daley said the M4 carbines "will be seldom used" and while he is an advocate of gun control, the decision to equip officers with the rifles was "not difficult."
"The weapons of criminals are getting bigger and bigger," he said. Chicago Police SWAT teams are equipped with M4 carbines, but police officers are currently only allowed to carry handguns. The M4 is a short assault rifle used by the U.S. Marine Corps. It fires more shots in less time than most handguns.