What is National Guard in the US and when are they deployed?

The US National Guard operates under both state and federal authority, making it a key force in handling emergencies from natural disasters to civil unrest.

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This explainer details its structure, historical deployments—including rare presidential orders—and examines its role amid recent protests over immigration raids in California. As demonstrations turned violent in San Francisco and Los Angeles, President Trump's decision to deploy the Guard has drawn comparisons to previous moments of national crisis.

The National Guard is a unique component of the US military system, serving both state and federal governments. It serves as the primary combat reserve force for the US Army and Air Force, composed of part-time soldiers who can be mobilized for domestic emergencies or overseas missions.

Each US state, territory and Washington, DC, maintains its own National Guard unit. The dual authority structure means the Guard answers to both state governors and the President of the United States. This flexibility sets it apart from other branches of the military.