President Donald Trump's deployment of the National Guard into several US cities has drawn a round of legal challenges by state and local officials.
Trump argues the use of federal troops is necessary to quell violence in Democratic-controlled cities, crack down on crime and support his deportation initiatives.
But several Democratic governors have pushed back, saying the deployments are unnecessary and risk escalating tensions.
Illinois filed a lawsuit on Monday asking a judge to block the deployment of troops to Chicago, while a federal judge on Sunday temporarily blocked the deployment of National Guard members from Texas and California to Portland, Oregon.
As the legal battles continue, here's what to know about the National Guard:
