During Monroe's seventh annual message to Congress on December 2, 1823, he created what has since been called the Monroe Doctrine, one of the most important foreign policy doctrines in American History. With this doctrine, he made it clear that there would be no European colonization in the Americas or any interference with independent states. Presidents have used this doctrine through the years as they have asserted to right to intervene in nations in this hemisphere. For example, John Tyler cited it as he seized Texas for America. Theodore Roosevelt extended the doctrine with the Roosevelt Corollary which basically stated that European nations could not use force in Latin America to collect debts.
Interestingly enough, the roots of isolationism that caused reticence to enter 'European' conflicts such as World War I and World War II can also be found in this speech where Monroe states, "In the wars of the European powers, in matters relating to themselves, we have never taken any part, nor does it comport with our policy to do so. It is only when our rights are invaded, or seriously menaced, that we resent injuries, or make preparation for our defence." Monroe also asserts that the US policy in regards to Europe is "...not to interfere in the internal concerns of any of its powers; to consider the government de facto as the legitimate government for us; to cultivate friendly relations with it, and to preserve those relations by a frank, firm, and manly policy; meeting, in all instances, the just claims of every power; submitting to injuries from none."
Following are a few key excerpts from this speech:
...[This] occasion has been judged proper for asserting, as a principle in which the 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 powers....
We owe it, therefore, to candor, and to the amicable relations existing between the United States and [European] 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 maintained 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 towards the United States.
It is impossible that the allied powers should extend their political system to any portion of either continent, without endangering our peace and happiness: nor can any one believe that our Southern Brethren, if left to themselves, would adopt it of their own accord. It is equally impossible, therefore, that we should behold such interposition, in any form, with indifference.