Respuesta :
The most direct cause for the beginning of America's involvement in Cuba just prior to the outbreak of hostilities was "the U.S.S. Maine being blown up," since this led to calls of war in the US.
I believe the answer is: the U.S.S. Maine being blown up
U.S.S maine was one of the battleship which belonged to united states, which was attacked by the Spanish during Cuba's uprising against the Spanish government. This create a tension between united states and Spain which resulted in United States helping Cuba to obtain their independence.