Okay, maybe you could argue that this foreign intervention was in defense of U.S. citizens, attacked on the high seas. But other Jeffersonian interventions were not so easily justified. Jefferson’s Louisiana Purchase from France was the carrot; the threat of American invasion was the stick that encouraged Napoleon to make the sale. Jefferson sent troops into Spanish West Florida as a similar incentive for Spain to cede the lands to the United States. Jefferson’s successors James Madison and James Monroe continued to intervene, sending troops into Spanish West Florida to force transfer. The War of 1812 was also not a defensive war; while the U.S. had legitimate complaints against the British government, the invasion of Canada was driven at least in part by the desire to add those lands to the United States.
There simply is not enough room to fully explore how fundamentally the United States has always had an interventionist foreign policy. Often, it has been with embarrassing objectives, such as the expansion of slavery through the Mexican War. Sometimes, it has been in pursuit of legitimate human rights concerns, such as the concentration camps in Cuba which led (in part) to the Spanish-American War. (This photograph of a mountain of skeletons at a concentration camp near Havana was taken by the great-grandfather of a student.)
Of course, good intentions are not enough. There are foreign interventions in which the United States has stepped in it good and proper, such as Somalia, where the intentions were good, but the results were not. Sometimes, the motives are hard to figure out in hindsight. As an example, the U.S. has a long history of intervention in Central America, especially in Nicaragua. I spent a very long time reading through 1909 newspapers, trying to figure out which of several theories for why the U.S. intervened actually make sense. At the end of my research, I concluded that there were likely multiple motives, including protection of U.S. citizens in the Bluefields area, and those who attempt to cast it strictly as a crass intervention on behalf of United Fruit’s interests have oversimplified it.
There are other interventions, such as the overthrow of Prime Minister Mossadegh in Iran in 1953, which look worse in hindsight than they did at the time. Cold War geopolitical concerns often trumped our own ideals about democracy and human rights. Depressingly enough, in some parts of the Third World, there were no good guys — just different groups of thugs exploiting the peasants. There were many times when local political leaders used the Cold War to manipulate the superpowers in ways that were not in the best interests of anyone but the local thug wearing a uniform with too many medals. Short of occupying the country, democracy — even relatively benevolent dictatorship — was not an option. In this respect, the Iraq War, for all its failings, was at least making an honest attempt to re-establish a democratic republic, and not just putting a new thug in charge.
I certainly agree that the U.S. should exercise considerable care in deciding where to intervene, and when. Still, I find the whole non-interventionist foreign policy idea like much else of libertarian thought: a beautiful ideal, but not terribly practical for the messy world in which we live.