In the discussions to which this interest has given rise, and in the arrangements by which they may terminate, the occasion has been deemed proper for asserting as a principle in which rights and interests of the United States are involved, that the American continents, by the free and independent condition which they have assumed and maintain, are henceforth not to be considered as subjects for future colonization by any European power. . . . We owe it, therefore, to candor and to the amicable relations existing between the United States and those powers to declare that we should consider any attempt on their part to extend their system to any portion of this hemisphere as dangerous to our peace and safety. With the existing colonies or dependencies of any European power we have not interfered and shall not interfere. But with the governments who have declared their independence and maintain it, and whose independence we have, on great consideration and on just principles, acknowledged, we could not view any interposition for the purpose of oppressing them or controlling in any other manner their destiny by any European power in any other light than as the manifestation of an unfriendly disposition toward the United States.As we all know, western expansion became a pillar of American strength throughout the 19th century. To "Go West" was as American a concept as apple pie. With that said, we would do well to remember that President James Monroe's passionate determination to safeguard western expansion from the clutches of European "invasion" was a bold pronouncement for that time. It may seem commonplace for us today, but it wasn't for the people of his day.
And as wonderful as Western expansion may have been for early Americans, it was a complete disaster for other groups, Native Americans in particular. What became known as "Manifest Destiny" in the eyes of Americans was nothing more than a fancy way of saying "conquest" for Native American tribes, who found themselves being continuously pushed further west. "Manifest Destiny" would eventually be used to justify war with Mexico (which, in reality, was one of the most unjustifiable wars in American history), along with other atrocities like the "Trail of Tears."
Of course, not all of the blame can or should be placed at the feet of James Monroe, who in my opinion is one of our most underrated presidents ever. Many other leaders (and lay folk) carry much of the responsibility for causing so much pain to Native Americans that, in some respects, remains to this day (President Andrew Jackson certainly comes to mind).