The United States has performed the most interesting violations of international law with regard to Latin America.  The Cuban Missile Crisis stands as one of the most famous of these, so it comes first.  Make no mistake:  I do not purport to judge the wisdom of these actions; rather, I merely wish evaluate their legality.

For the uninitiated, this crisis erupted in 1962 upon AmericaÌs discovering that the Soviet Union was furtively supplying intermediate-range nuclear weapons to Cuba.  Cuba, by the way, rests a mere 90 miles from Florida.  After frantically considering several options, the Kennedy administration decided to throw a naval blockade (what they euphemistically called a 'quarantine') around Cuba to thwart the vessels carting the nukes.  Here it is important to understand international law:  a blockade is an act of war, but supplying arms to an ally is not (especially in light of the fact that the United States had several nukes stationed in Greece and Turkey, right at the USSR's doorstep).  Because the blockade was not in response to an illegal act of war, it constituted an illegal, aggressive use of force in violation of Article 2(4) of the UN Charter.  Enforcement actions of this kind might become legal if the Security Council later blesses them, but this did not occur here.

Some have argued that Security Council silence amounts to an allowance of enforcement action, but this is ridiculous.  If that were so, the United States could invade and conquer countries and thereafter veto any Security Council measures, thereby eviscerating the entire Charter.  Even if we were to stretch the scope of 'self-defense' to include anticipatory actions such as this one, this argument defeats itself because the USSR looks fully justified in responding to our placing nukes in Turkey and Greece.

Consequently, the U.S. agreed to withdraw those missiles in exchange for Kruschev's withdrawing his from Cuba.
 

Visit ThinkQuest's "Crisis Center" for an entertaining look at the Cuban Missile Crisis.  ThinkQuest is an annual contest for teenage students to create educational web-pages.  Judging by this particular interactive site, they've done a good job.

Visit the Avalon Project at Yale Law School for an exhaustive compilation of documents concerning the Cuban Missile Crisis.

For a liberal interpretation of overall U.S. policy towards Latin America, visit Foreign Policy In Focus

For a conservative viewpoint on Latin America policy, visit the Heritage Foundation