Answer;
The United States had monetary interests in Cuba and wanted to protect them
The United States break its policy of isolationism in reference to Cuba because it had monetary interests in Cuba and wanted to protect them.
Step-by-step explanation;
Cuba had a lot of goods and materials such as sugar that would benefit the United states and the Europe.
Spanish ruling Cuba meant that the U.S could not persue their economic interests and benefits from goods such as sugar, for this reason they needed Cuba to become freelance so that it may work with them.