As the war in Southeast Asia wound down, the Joint Chiefs of Staff began a slow and sometimes uncomfortable reassessment of their military plans and policies. Similar reassessments had followed previous wars and invariably had given rise to passionate inter-Service rivalries and intense competition for resources. Some of these elements, to be sure, were present in the aftermath of Vietnam. But compared to the build-downs that followed World War II and Korea, the transition following Vietnam was relatively smooth and easy. Indeed, the most serious problems that arose were in developing military policies and a force posture compatible with a rapidly changing international environment dominated by the prospect of a new era in Soviet-American relations known as "détente.”

On March 31, 1968, President Lyndon B. Johnson announced over national television that he would not seek reelection and would instead devote the remainder of his tenure in the White House to finding a peaceful settlement in Vietnam. At home, the President faced a rising crescendo of protests against the war, mounting economic difficulties brought on by war-induced inflation, and challenges to his political leadership from Senators Eugene McCarthy and Robert F. Kennedy. Meanwhile, in Vietnam, recent heavy fighting—the Communist Tet offensive and the ongoing battle for Khe Sanh—had shattered administration predictions that the United States was winning and that the war would soon be over. With an American-imposed solution appearing less and less feasible, the President ordered a halt to the bombing of North Vietnam above the twentieth parallel. Henceforth, the United States would concentrate on strengthening the South Vietnamese armed forces to resist Communist aggression on their own. Since committing U.S. combat forces to Vietnam 3 years earlier, the United States had yet to suffer a major defeat. But it had also been unable to score a decisive victory. As a practical matter, President Johnson’s announcement was the first step toward U.S. disengagement from Vietnam, a process that would still take 5 more years to yield what his successor, Richard M. Nixon, termed "peace with honor.”

The scene was reminiscent of many amphibious operations of World War II. On the morning of March 8, 1965, with a light mist reducing visibility, elements of 9th Marine Expeditionary Brigade landed on a sandy beach near Da Nang, South Vietnam. Wading ashore with their gear, they encountered reporters, photographers, the mayor of Da Nang, and their commander, Brigadier General Frederick J. Karch, whom local school girls had laden with garlands in celebration of the occasion. A cordial welcome, it belied the presence of Viet Cong guerrillas a few miles away. Climbing into waiting trucks, the Marines were transported to the nearby American air base to take up security duties. The vanguard of a larger U.S. presence yet to come, these Marines were the first American combat troops to arrive in Vietnam. "Americanization” of the Vietnam War had begun. It was a policy the Joint Chiefs of Staff had helped to shape, but not one that gave them much satisfaction or sense of confidence. The war in Vietnam was entering a new phase, and with it came growing uncertainty among the JCS whether they would have the tools and resources at their disposal to make that policy succeed.