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DoD
DoD
The Department of Defense
I believe you're referring to the "Defense Support to Civil Authorities" (DSCA).
DoD
exceed local need
The federal government
No such thing as martial (marshall) law in Canada, unless we have a civil war
During the American Civil War, soldiers for both sides of the conflict came from all walks of life. Initially relying on volunteers, both the South and the North engaged creatively in various campaigns (including conscription) later in the war in order to maintain the ranks of their armed forces.
The US government wanted to remove Saddam Hussain from office in Iraq in 2003, Operation Iraqi Freedom; US forces removed him, arrested him, and turned him over to the Iraqi authorities. From 2003 to present, there has been no organized government in Iraq that can establish and maintain law, order, and stability in the nation. The US/Coalition and the current Iraqi Government is trying to establish/maintain law, order, and stability within it's own country; but relies heavily upon US/Coalition forces to police their crime rate (terrorists/insurgents).
The Allied forces got involved in the Russian Civil War in order to back the anti-Bolshevik White forces. The Allies were worried after the collapse of the Eastern front.
They hoped to prevent Communism from taking hold.