Which U.S. President is recognized for asserting extensive control over foreign policy during the early 20th century?

The assertion of extensive control over foreign policy during the early 20th century is most closely associated with Theodore Roosevelt. He transformed the role of the presidency in international affairs, demonstrating an assertive approach to foreign policy that included the use of military force. Roosevelt was well-known for his motto "speak softly, and carry a big stick," which emphasized diplomacy backed by the threat of military action.

His presidency saw significant involvement in global affairs, such as the negotiation of the end of the Russo-Japanese War, for which he won the Nobel Peace Prize, and the construction of the Panama Canal, showcasing his willingness to take bold action on the world stage. Roosevelt's foreign policy initiatives often set a precedent for increased presidential power in diplomatic matters, distinguishing him as a pivotal figure in the evolution of U.S. foreign policy during that era.