It was time to grant Cuba its freedom. However, the American's wanted safeguards in place to insure that Europeans didn't take advantage of the inherent weakness of a fledgling nation. There was no fear of Spain returning. It was bereft of the will as well as the resources to risk another confrontation with the United States. France and England were too distracted with problems in other parts of their far-flung empires. However, Germany was beginning a rise to power. It had a modern navy and seemed interested in establishing bases in the Caribbean to support adventures in South America.
Some American statesmen argued that the Monroe Doctrine would discourage German incursions. Others argued that it was only policy. A law was needed. The first such law they advanced was the Teller Amendment, to be embedded in the thread of war against Spain. It announced America's intentions, not only to the Spanish, but also to the rest of the world.
We see this same mistake echoed throughout history. Most recently, America was accused of invading Iran to seize its oil. Even now that American forces have been withdrawn and not one drop of oil was purloined, people, even in the United States, continue to make the charge. They seem incapable of imagining any motivation other than greed. Is it possible that they are misguided by their own base intentions?