<P> After the opening of the island to world trade in 1818, trade agreements began to replace Spanish commercial connections . In 1820 Thomas Jefferson thought Cuba is "the most interesting addition which could ever be made to our system of States" and told Secretary of War John C. Calhoun that the United States "ought, at the first possible opportunity, to take Cuba ." In a letter to the U.S. Minister to Spain Hugh Nelson, Secretary of State John Quincy Adams described the likelihood of U.S. "annexation of Cuba" within half a century despite obstacles: "But there are laws of political as well as of physical gravitation; and if an apple severed by the tempest from its native tree cannot choose but fall to the ground, Cuba, forcibly disjoined from its own unnatural connection with Spain, and incapable of self support, can gravitate only towards the North American Union, which by the same law of nature cannot cast her off from its bosom ." </P> <P> In August 1851, 40 Americans who took part in Narciso López's filibustering expedition in Cuba, including William L. Crittenden, were executed by Spanish authorities in Havana . In 1854, a secret proposal known as the Ostend Manifesto was devised by U.S. diplomats, interested in adding a slave state to the Union . The Manifesto proposed buying Cuba from Spain for $130 million . If Spain were to reject the offer, the Manifesto implied that, in the name of Manifest Destiny, war would be necessary . When the plans became public, because of one author's vocal enthusiasm for the plan, the manifesto caused a scandal, and was rejected, in part because of objections from anti-slavery campaigners . </P> <P> By 1877, Americans purchased 83 percent of Cuba's total exports . North Americans were also increasingly taking up residence on the island, and some districts on the northern shore were said to have more the character of America than Spanish settlements . Between 1878 and 1898 American investors took advantage of deteriorating economic conditions of the Ten Years' War to take over estates they had tried unsuccessfully to buy before while others acquired properties at very low prices . Above all this presence facilitated the integration of the Cuban economy into the North American system and weakened Cuba's ties with Spain . </P> <P> As Cuban resistance to Spanish rule grew, rebels fighting for independence attempted to get support from U.S. President Ulysses S. Grant . Grant declined and the resistance was curtailed, though American interests in the region continued . U.S. Secretary of State James G. Blaine wrote in 1881 of Cuba, "that rich island, the key to the Gulf of Mexico, and the field for our most extended trade in the Western Hemisphere, is, though in the hands of Spain, a part of the American commercial system...If ever ceasing to be Spanish, Cuba must necessarily become American and not fall under any other European domination ." </P>

How did the us maintain political control over cuba