In May 1959 Castro introduced a programme of agrarian reform - considerable amounts of US property in Cuba were seized by the state.
This did not cause a major, hostile US response.
However, when Soviet First Deputy Premier, Mikoyan, visited Cuba in February 1960 and arranged $100 million in credits with Castro, US fears of Cuba becoming a Soviet satellite in the Caribbean were heightened.
Cuba were now in both a political and economic relationship with the USSR.