When the United States joined the race for empire at the end of the 19th century, that was the tactic it used. It sent a large expeditionary force to the Philippines to crush an independence movement, ultimately killing some 200,000 Filipinos. At the other end of the carnage spectrum, it seized Guam without the loss of a single life and Puerto Rico with few casualties. Every time, though, U.S. victory was the result of superior military power. In the few cases when the United States failed, as in its attempt to defend a client regime by suppressing Augusto Cesar Sandino’s nationalist rebellion in Nicaragua during the 1920s and 30s, the failure was also the product of military confrontation. For the United States, as for all warlike nations, military power has traditionally been the decisive factor determining whether it wins or loses its campaigns to capture or subdue other countries. World War II was the climax of that bloody history.

After that war, however, something important changed. The United States no longer felt free to land troops on every foreign shore that was ruled by a government it disliked or considered threatening. Suddenly there was a new constraint: the Red Army. If American troops invaded a country and overthrew its government, the Soviets might respond in kind. Combat between American and Soviet forces could easily escalate into nuclear holocaust, so it had to be avoided at all costs. Yet during the Cold War, the United States remained determined to shape the world according to its liking — perhaps more determined than ever. The United States needed a new weapon. The search led to covert action.

A news agency

During World War II the United States used a covert agency, the Office of Strategic Services, to carry out clandestine actions across Europe and Asia. As soon as the war ended, to the shock of many OSS agents, Harry Truman abolished it. He believed there was no need for such an agency during peacetime. In 1947 he changed his mind and signed the National Security Act, under which the Central Intelligence Agency was established. That marked the beginning of a new era. Covert action replaced overt action as the principal means of projecting American power around the world.

Truman later insisted that he had intended the CIA to serve as a kind of private global news service. “It was not intended as a ‘Cloak & Dagger Outfit!’” he wrote. “It was intended merely as a center for keeping the President informed on what was going on in the world … [not] to act as a spy organization.