President Donald Trump says his administration will send “a surge” of federal agents to US cities in an anti-crime initiative, Operation Legend.
Speaking from the White House, Mr Trump said he had “no choice” but to deploy hundreds of federal agents to Chicago.
He is also expanding federal law enforcement in Kansas City, Missouri, and Albuquerque, New Mexico.
Federal officers are already in Portland, Oregon, where the mayor says they are making ongoing protests worse.
US Attorney General William Barr, who joined Mr Trump at Wednesday’s announcement, said they had already sent about 200 federal agents to Kansas City, would send a “comparable” number to Chicago, and about 35 others to Albuquerque.
President Trump, a Republican, is adopting a law-and-order posture as he runs for re-election in November amid ongoing racial justice protests that have sometimes descended into civil disorder.
On Tuesday night, federal agents fired tear gas, pepper balls and flashbangs at demonstrators in central Portland, which has seen 54 consecutive night of protests.
The officers quickly used crowd-control munitions in an attempt to disperse hundreds of people gathered outside a federal court.