The U.S. does prevent trade with other countries. From https://en.wikipedia.org/wiki/United_States_embargo_against_Cuba https://en.wikipedia.org/wiki/United_St

The U.S. does prevent trade with other countries. From https://en.wikipedia.org/wiki/United_States_embargo_against_Cuba https://en.wikipedia.org/wiki/United_States_embargo_against_... “In 1999, President Bill Clinton expanded the trade embargo by also disallowing foreign subsidiaries of U.S. companies to trade with Cuba.“ “The United States has threatened to stop financial aid to other countries if they trade non-food items with Cuba.” I was there in the brief time when U.S. citizens were permitted by the U.S. government to visit on cruises. During my stay, I was constantly reminded that I was disallowed to spend money there on unsanctioned activities.