Here is a very interesting excerpt from a speech by Major General Smedley Butler (USMC). You can read the whole thing (the excerpt is quite short), but this paragraph just about sums it up for me:
I helped make Mexico, especially Tampico, safe for American oil interests in 1914. I helped make Haiti and Cuba a decent place for the National City Bank boys to collect revenues in. I helped in the raping of half a dozen Central American republics for the benefits of Wall Street. The record of racketeering is long. I helped purify Nicaragua for the international banking house of Brown Brothers in 1909-1912 (where have I heard that name before?). I brought light to the Dominican Republic for American sugar interests in 1916. In China I helped to see to it that Standard Oil went its way unmolested.