Any discussion of how Republicans find themselves so adrift on national security has to begin with President Reagan, who road-tested the peace-through-strength worldview with the largest peacetime defense buildup in the nation’s history. In truth, however, Reagan never reconciled the party’s instincts for low taxes and high defense spending, and the national debt more than tripled on his watch. He saved his legacy only by winning the Cold War, which allowed for a roughly one-third reduction in defense spending during the 1990s.

During President Clinton’s two terms, Republicans in Congress openly flirted with isolationism. They refused to pay U.S. dues to the United Nations, voted down the Comprehensive Test Ban Treaty, and criticized the Balkan interventions as “Clinton’s wars.” Foreshadowing Paul’s vision of domestic drone assassinations, certain Republicans imagined the “black helicopters” of a one-world government flying over U.S. territory. Starting in the late 1990s, neoconservatives called for an aggressive foreign policy to confront tyrants, and by the time George W. Bush had been elected president, they’d won the argument. They restored their party’s pro-defense penchant, and many of them took top jobs in the administration.

But the neocons’ advocacy for the Iraq war—and close association with that debacle—sent the party back to the foreign policy drawing board. Romney tried to dust off the peace-through-strength mantra, but the country was sick of war, and the momentum within the GOP had swung back to the small-government and libertarian factions. “Part of this is generational change, because while a number of the older defense hawks in Congress were focused in recent years on trying to stay the course in Iraq and Afghanistan, the intellectual energy in the Republican Party shifted,” says Thomas Donnelly, a defense analyst at the conservative American Enterprise Institute. “Unfortunately for the U.S. military, that dynamic suggests that we can’t even see where the bottom in defense spending lies yet.”