Cuba and the Platt Amendment

Although the Teller Amendment ruled out annexing Cuba, the United States did not leave the island fully independent. The US Army occupied Cuba from 1898 to 1902, building schools and sanitation systems; during this period Cuban physician Carlos Finlay's theory that mosquitoes spread yellow fever was confirmed by a US Army commission led by Walter Reed. In 1901 Congress passed the Platt Amendment, which Cuba was required to include in its constitution.

It gave the United States the right to intervene in Cuban affairs, limited Cuba's ability to make treaties and borrow, and required Cuba to lease land for naval bases, leading to the base at Guantánamo Bay in 1903. Cuba became formally independent in 1902, but US troops returned in 1906–09 and later. Many Cubans saw the amendment as a betrayal of their independence struggle, and historians often describe Cuba in this period as a protectorate in practice. The amendment was repealed in 1934, except for the Guantánamo lease.