Answer:
The United States established the Monroe Doctrine because it was concerned that Europeans would regain colonies in Latin America and hurt trade.
Explanation:
The Monroe Doctrine reaffirmed the position of the United States against European colonialism, inspired by the isolationist policy of George Washington, and that developed the thought of Thomas Jefferson, according to which "America has a Hemisphere for itself", which could mean both the American continent and its own country.
The United States government, then a newly independent country that had achieved independence only 40 years from then, feared that the victorious European powers emerging from the Congress of Vienna (1814-1815) would revive their colonial empires in the Americas. As the revolutionary Napoleonic wars (1803-1815) ended, Prussia, Austria and Russia formed the Holy Alliance to defend monarchism. In particular, the Holy Alliance authorized military incursions to reestablish the dominion of the Bourbons over Spain, as well as under their colonies, which were at the time establishing their independence.
At the time, the Monroe Doctrine represented a serious warning not only to the Holy Alliance, but also to Great Britain itself, although its immediate effect, in terms of defending the new American states was purely moral, given that the economic interests and the political and military capacity of the United States at the time did not surpass the Caribbean region. It is very important to note that the United States at this time was still far from being considered even a regional power. In any case, the formulation of the Doctrine helped Great Britain to thwart the European plans of recolonization of America and allowed the United States to continue expanding its borders to the west.