The Republican Party is undergoing its most significant foreign policy debate since President Richard Nixon dismissed then-California Gov. Ronald Reagan as “shallow” and of “limited mental capability” and Reagan criticized the policy of detente, initiated by Nixon, as “a one-way street that the Soviet Union has used to pursue its own aims.”

Once in the Oval Office himself, President Reagan proved willing to engage in negotiations with the Soviet Union. He also, in a series of national security directives, set out the objective of winning the Cold War by undermining Soviet power in Eastern Europe, disrupting the Soviet economy and rolling back Soviet influence at every opportunity. And he publicly addressed the reality of Soviet communism — its inherent coercion and violence — in frankly moral terms.

Over the past few years, Reagan’s internationalism, moralism and strategic aggressiveness have been out of favor in much of the GOP. Many elected Republicans grew tired of defending George W. Bush-era interventions in Iraq and Afghanistan and the global exertions of the war on terrorism. With the arrival of President Obama, they no longer had a political imperative to do so. It became possible and convenient for conservatives to attack Obama and international engagement at the same time.

Sen. Rand Paul (R-Ky.) was just the man to lead the backlash, given his marination in the isolationism of his father’s foreign policy. In 1987, Ron Paul formally resigned from the GOP, protesting Reagan’s “indiscriminate military spending, an irrational and unconstitutional foreign policy, zooming foreign aid, the exaltation of international banking, and the attack on our personal liberties and privacy.” Rand Paul has provided a version of the same critique against an easier target: Obama. The younger Paul has proposed defense cuts, criticized foreign aid, led opposition to U.S. involvement in Syria, raised the possibility of accepting and containing a nuclear Iran and railed against “possible targeted drone strikes against Americans on American soil.”

His reaction to the Ukrainian crisis has been revealingly typical. As Russian troops massed, Paul said, “Some on our side are so stuck in the Cold War era that they want to tweak Russia all the time, and I don’t think that is a good idea.” And he seemed to signal the legitimacy of Russian claims: “The Ukraine has a long history of either being part of the Soviet Union or within that sphere.”

Paul has attempted to associate his foreign policy with the realism of Henry Kissinger. It is not a good fit. Realism has generally asserted the need for a strong executive in conducting global strategy. Paul apparently believes that U.S. presidents can’t be trusted with sophisticated weapons lest they kill Americans in cafes. His approach is not realism but non-interventionism. His libertarian foreign policy holds that America is less secure because it has been “too belligerent” and that decades of international engagement have both corrupted our constitutional order and corrupted other nations with our largess or militarism. This perspective sometimes overlaps with foreign policy realism but only in the narrow cases when both recommend disengagement. Paul has a trumpet that only sounds retreat.

For a while, it seemed that Paul’s views were sweeping the GOP. Now we are witnessing the beginnings of a backlash to his backlash, aided by Vladimir Putin. Americans may not have suddenly developed a keen humanitarian concern for Ukrainians, but a revanchist Russia is the type of threat that has mobilized conservatives in the past. While a “let them fight it out” argument may play well concerning Syria, a “let Putin get away with it” argument is a harder sell. The partisan momentum in the GOP is no longer entirely on the side of disengagement. Across the party, a Reaganite critique of Obama’s foreign policy stirs.

For evidence, look no further than Sen. Ted Cruz (Tex.), who possesses the GOP’s most sensitive instrument to determine the fluctuation of populist energies. In the aftermath of the Ukraine invasion, Cruz criticized Paul for insufficient fidelity to Reagan’s belief that “U.S. leadership is critical in the world.” Paul has been on the defensive, belatedly referring to Russia as a “rogue nation.” And he has tried to claim credit for the fact that Western nations are not sending troops to the Crimean Peninsula — which no one has actually considered since the Crimean War ended in 1856.

Paul is left to insist, “I’m a great believer in Ronald Reagan.” This amounts to a serious concession, since Reagan would not have returned the compliment.

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