Well.. the threat of a good example / the domino effect threat / the threat of hurting profits and hurting the easy exploitative access to resources
Adding some quotes from the book from the book "The Untold History Of The United States" by Oliver Stone & Peter Kuznick
"In February 1901, while U.S. troops were, in McKinley’s words, uplifting, civilizing, and Christianizing the Filipinos, the U.S. Congress dispelled any lingering illusions regarding Cuban independence. It passed the Platt Amendment, which asserted the United States’ right to intervene in future Cuban affairs, limited the amount of debt Cuba could accumulate, restricted Cuba’s power to sign treaties, and gave the United States a naval base at Guantánamo Bay, which would secure the eastern approach to the Isthmus of Panama. The United States made clear that the army would not leave until the amendment was incorporated into the Cuban Constitution. After the war, American businessmen swooped in, grabbing all the assets they could seize. United Fruit Company gobbled up 1.9 million acres of land for sugar production at 20 cents per acre. By 1901, Bethlehem Steel and other U.S. businesses may have owned over 80 percent of Cuban minerals."
"U.S. interests and prestige were dealt another devastating blow when revolutionaries, led by Fidel Castro and Che Guevara, toppled Cuba’s U.S.-friendly dictator, Fulgencio Batista, on New Year’s Day 1959. American corporations had dominated the island since 1898. In 1959, they controlled more than 80 percent of Cuba’s mines, cattle ranches, utilities, and oil refineries, 50 percent of the railroads, and 40 percent of the sugar industry. The United States still retained its naval base at Guantánamo Bay. Castro quickly set about reforming the education system and redistributing land. The government seized more than a million acres from United Fruit and two other American companies. When the United States tried to strangle the new regime economically, Castro turned to the Soviet Union for aid. On March 17, 1960, Eisenhower instructed the CIA to organize a “paramilitary force” of Cuban exiles to overthrow Castro."
And more generally, in the context of Vietnam:
"In April 1954, Ho Chi Minh’s peasant liberation army, commanded by General Vo Nguyen Giap, and peasant supporters hauled extremely heavy antiaircraft guns, mortars, and howitzers through seemingly impassable jungle and mountain terrain to lay siege to desperate French forces at Dien Bien Phu. Incredibly, the United States was then paying 80 percent of the French costs to keep the colonialists in power. Eisenhower explained in August 1953, “when the United States votes $400,000,000 to help that war, we are not voting a giveaway program. We are voting for the cheapest way that we can to prevent the occurrence of something that would be of a most terrible significance to the United States of America, our security, our power and ability to get certain things we need from the riches of the Indonesia territory and from Southeast Asia.” He envisioned countries in the region falling like dominoes, ultimately leading to the loss of Japan. Nixon agreed: “If Indochina falls, Thailand is put in an almost impossible position. The same is true of Malaya with its rubber and tin. The same is true of Indonesia. If this whole part of Southeast Asia goes under Communist domination or Communist influence, Japan, who trades and must trade with this area in order to exist, must inevitably be oriented towards the Communist regime.” And U.S. News & World Report cut entirely through any rhetoric about fighting for the freedom of oppressed peoples and admitted, “One of the world’s richest areas is open to the winner in Indochina. That’s behind growing U.S. concern . . . tin, rubber, rice, key strategic raw materials are what the war is really about. The U.S. sees it as a place to hold— at any cost.” "