The National Guard is a reserve force of the U.S. military that is typically deployed by states in response to natural disasters, although it has been used in the past by presidents to help quell domestic unrest - including President George H.W. Bush during the Los Angeles riots in 1992.

From upholding civil rights rulings to quelling civil disturbances and even delivering mail, other presidents have sent out National Guard units.

In an unprecedented move, President Trump has deployed 850 National Guard members to Washington, DC, leveraging the Home Rule Act of 1973 to federalize the city's Police Department for a month, ostensibly to tackle crime and homelessness.