Chicago has been a focus for the Department of Homeland Security in recent weeks, amid the immigration crackdown in Illinois.
United States Immigration and Customs Enforcement agents have arrested people outside schools, restaurants and public spaces.
There have often been violent confrontations with protesters, as federal agents have released tear gas and fired pepper balls into angry crowds.
Pritzker says ICE is causing mayhem, chaos and confusion. He is warning that other cities could soon face the same fate.
"Masked federal agents from ICE and CBP are on the ground terrorizing our communities with tear gas and rubber bullets, and some are wearing camouflage uniforms that could easily be mistaken for the military. It is Trump and Miller's agents, were operating like they are his own secret police, harassing civilians, tear gassing communities and arresting journalists and grabbing people in the street to ask them for their papers based on the color of their skin. This is intentional," Pritzker said.
The National Guard is in a holding pattern in Illinois, until their deployment from President Donald Trump is decided in the courts.
The retired military leaders expressed grave concern about Trump's continued abuse of power and attempts to politicize the military, a news release from Pritzker's office said.
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"I'm grateful to have the clarity given by the retired generals, rear admirals, and veterans here with me today. With their combined wealth of experience, I have been hearing from them about what this dangerous power grab by the Trump administration means for our state," Pritzker said. "One thing is evident: this effort to deploy troops in American cities is not normal. There is no justification for such a deployment, and it echoes the rise of authoritarian regimes throughout world history. Illinois is not a place you can conquer. And our people are not your subjects. Period."
The veterans condemned using the National Guard for something other than foreign combat and natural disasters.
"They should not be treated as props for political theater," said Maj. Gen. William Enyart, who is retired from the Illinois National Guard.
Enyart and others said calling up citizen soldiers for policing purposes is not only dangerous but threatens recruiting, retention and readiness of the Guard.
"Pulling them out of their communities doesn't just disrupt readiness. It leaves holes in our local safety nets. It means fewer first responders on the job. It means missed paychecks," said Janessa Goldbeck, CEO of Vet Voice and a former Marine.
Former military members say the hidden costs of misusing the National Guard are immense.
Enyart says watching soldiers pick up trash or spread mulch in Washington, D.C. can affect recruitment and their real jobs while they are deployed.
"As an employer, you got to hire him back, right? But that next employer you hire doesn't have to be a guardsman; that's an impact," Enyart said.
In addition, generals are concerned about the lines being blurred between ICE agents and active duty soldiers.
"When we blur that line, we risk turning our own streets into battlefields and our citizens into potential enemies," retired U.S. Army Maj. Gen. Randy Manner said.
Despite not being trained in the military, ICE agents are wearing combat fatigues and boots.
"I think the modern term is cosplaying. I would say, pretending to be soldiers. They're not soldiers. And it is, it is a smirch on the National Guard's reputation for them to be wearing the same uniform as we are," Enyart said.