What does the Monroe doctrine prohibit?

It prohibited other countries such as Spain and Russia from entering US territories.

Explanation:

The Monroe Doctrines purpose was to establish western dominance towards other countries.

The Monroe Doctrine prohibited the involvement of the European nations in the Western Hemisphere, which if done, will be deemed as a hostile act of threat.

Explanation:

The Monroe Doctrine of the United States was a doctrine or set of rules that were made during the time of President James Monroe at his State of the Union Address to the Congress. In his speech, he emphasized on the need for a separate and yet binding law that will ensure the European nations will have no attempts to try to hold power or colonize any place in the American regions.

In this doctrine, it stated that the European nation has no right or obligation to interfere in the Western hemisphere. If this is to occur, then it will be accepted as an act of hostility, to which the United States will be forced to retaliate. It also stated that the U. S. will not interfere in any of the political situations or wars among the European powers, and that it will keep clear of any control over the existing colonies in it. It also prohibited the further colonization of the Western Hemisphere, claiming it is closed for any more colonization.