Answer:
He was in the sense that the United States was a threat to his regime, but he was not at the same time, in a moral and ethical sense, because he was himself a dictator, and the use of nuclear weapons had the goal of strengthening the grip of his power.
When Castro asked for nuclear weapons to the Soviet Union, he contributed to the escalation of the Cold War, which almost ended in a nuclear event. Castro could have tried to negotiate with John F. Kennedy, and above all, he should have made Cuba into a pluralist democracy where human rights are respected, instead of turning the island into a dictatorship.