When President James Monroe declared in 1823 that Europeans were no longer allowed to crush revolting colonies or expand further into the Americas, the US wasn't exactly powerful enough to enforce it. In spite of this, European attempts to colonise the region reduced massively and many kept to the Monroe doctrine's demands. But given that they didn't have to why did they and what did the US do when some Europeans broke it? To find out watch this short and simple animated history documentary.