The idea behind the 600-ship Navy can be traced back to the Vietnam War. During the war, the armed services rapidly expanded to meet the demands placed on them.
With the end of the Vietnam War, the American government reduced military spending. By 1978 Admiral James L. Holloway III concluded that the Navy had a very slim margin over its Soviet counterpart. The Soviet Union, which had been supporting North Vietnam, began staging their naval vessels from former US ports in South Vietnam. Building on this gain, Soviet vessels began to sail in all seven seas with increased vigor and even ventured into the Gulf of Mexico. Soviet forces also stepped up infantry, armor and air force deployments in Eastern Europe.
It was against this backdrop in 1980 that the United States began an election year. Ronald Reagan, a Republican, ran the presidential race on a platform that included improving the armed services, which appealed to then-current American concerns regarding Soviet military power. He continued this in 1984, releasing a campaign commercial, A bear in the woods, which played on the use of the bear as a national symbol of Russia, asked the rhetorical question, "Isn't it smart to be as strong as the bear?"
Eventually political pressure to reduce the national budget deficit resulted in Congress reversing itself and passing a series of declining defense budgets beginning in 1986. Weinberger clashed with Congress over the cuts, resigning in late 1987, and was succeeded by Frank Carlucci. Lehman's successor as Navy Secretary, Jim Webb, remained a fierce proponent of the expanded fleet, and disagreed with Carlucci over how to cut the Navy budget in line with other services. Webb resigned rather than endorse Carlucci's cut of 16 frigates. As revealed in The Reagan Diaries, Reagan reflected about Webb's resignation on 22 February 1988: "Present Sec. Webb resigned over budget cuts. I don't think Navy was sorry to see him go."
Following the dissolution of the Soviet Union in the early 1990s and the lack of a perceived threat against the United States, several of the Reagan Administration's policies and plans, such as the "600-ship Navy", were scaled back or abandoned. US bases across Europe and North America were slowly decommissioned and closed, others were mothballed through the Base Realignment and Closure process. In the Navy, this resulted in the retirement of several older carriers, the decommissioning of all four of the Iowa-class battleships and the cancellation of the remaining Seawolf-class submarines.