What was the most significant remnant of the Olmec civilization?

The platt amendment of 1901 forbade cuba from entering into any treaties that would allow undue foreign involvement in cuban affairs. this law was passed after the spanish-american war to make sure that european nations weren’t going to get involved with cuba. 1, why might the platt amendment be considered ironic? 2, what reasons would the united states have for not wanting european influence in cuba?