Two hundred Texas National Guard troops have arrived in Illinois, a Pentagon official said on Tuesday, ahead of a planned deployment in Chicago that is strongly opposed by local officials.

US President Donald Trump had already sent troops onto the streets of Los Angeles and Washington and has ordered them to Memphis, as well as Chicago and Portland, threatening to invoke emergency powers to forward such efforts if the courts get in the way.

In Memphis, police chief Cerelyn Davis told a city council meeting on Tuesday that she expected the National Guard deployment soon.

"It looks like maybe October 10 -- in a few days we'll see the first group of individuals come to our city," Davis said, adding that some commanders were already there to prepare for their arrival.

Trump -- who suggested last week that American cities be used as "training grounds" for US military forces -- exaggerated the scale of unrest in Los Angeles and crime in Washington to justify those deployments, and a judge suggested he did the same with Portland.

The troops from Texas were sent to Illinois as part of a mission to protect "federal functions, personnel, and property," the Pentagon official said on condition of anonymity, adding the Guardsmen had been mobilised for an initial period of 60 days.

The troops were seen on Tuesday at a military facility in Elwood, southwest of Chicago.

The planned deployment of those forces has infuriated Democratic Governor JB Pritzker, who said they "should stay the hell out of Illinois," and that any deployment against his state government's wishes would amount to an "invasion."

Trump authorised at the weekend the deployment of 700 National Guard troops to Chicago, sparking a lawsuit by Illinois state officials who accused him of using US troops "to punish his political enemies." (AFP)