American empire: a history of US imperial expansion

In December 1823, President James Monroe declared in his State of the Union address that “the American continents... are henceforth not to be considered as subjects for future colonisation by any European powers”, setting out a vision of US dominance over the New World.

Now, President Trump has revived the so-called Monroe Doctrine to justify his aggressive foreign policy in the Americas

Why was the Monroe Doctrine established?

In the years before Monroe’s address, Spain’s vast empire in the Americas had collapsed.