British Foreign Minister George Canning proposed that the US and the UK join to warn off France and Spain from intervention. Both Thomas Jefferson and James Madison urged Monroe to accept the offer, but John Quincy Adams was more suspicious. Adams also was quite concerned about Russia and Mexico's efforts to extend their influence over the joint British-American claimed territory of Oregon Country (see New Albion).
At the Cabinet meeting of November 7, 1823, Adams argued against Canning's offer, and declared, "It would be more candid, as well as more dignified, to avow our principles explicitly to Russia and France, than to come in as a cockboat in the wake of the British man-of-war."
He argued and finally won over the Cabinet to an independent policy. In Monroe's Annual Message to Congress on December 2, 1823, he delivered what we have come to call the Monroe Doctrine. Essentially, the United States was informing the powers of the Old World that the Americas were no longer open to European colonization, and that any effort to extend European political influence into the New World would be considered by the United States "as dangerous to our peace and safety." The United States would not interfere in European wars or internal affairs, and expected Europe to stay out of the affairs of the New World.
If you're looking for a place to apply the Monroe Doctrine, take a look where Venezula is getting its arms.