Opinion | A Free World Needs a Strong America

As recently as a decade ago, it would not have been hard to unite a broad majority of Republicans and Democrats around a shared idea of what America’s military power should be for.

Defense of the homeland. Deterrence of would-be aggressors. Cooperation with treaty allies and protection of kindred democracies confronting common foes. Humanitarian aid and relief. The security of the global commons: sea lanes, air corridors, undersea cables, digital networks. Upholding the laws of war.

In sum, the ability to prevent war wherever possible and win it whenever necessary — all for the sake of a safer, more open, rules-based world.

The Trump administration brings a starkly different mind-set to the issue. Out with the Department of Defense; back to the Department of War. Well-established rules of engagement have yielded to blowing up small boats on the high seas. In place of standing with Ukraine’s embattled democracy against Russia’s invasion, the administration has adopted a course of moral equivalence between the two sides while seeking profits from the war through arms sales and mineral deals.

As for the kind of military alliance-building that typified American foreign policy for much of the 20th century, President Trump has reverted to threats of conquest more common in the 19th. And this is to say nothing of his efforts to deploy troops to American cities, impose political loyalty tests on senior officers or hamstring reporters at the Pentagon.

Mr. Trump justifies his approach by claiming that the Pentagon needs an entirely different mentality for a new era of great-power rivalry. That’s not wrong. China’s rise and Russia’s revanchism means our security is more threatened today than it has been in decades. But so does the fact the United States has forfeited our military’s edge.

The president has done better than his predecessors in getting NATO allies to start budgeting adequately for their defense. He’s been right, also, to cut through layers of entrenched Pentagon bureaucracy that have prevented the military from keeping pace with technological changes that leave us increasingly vulnerable.

But Mr. Trump and his administration are grievously wrong to think the “America First” approach they’ve adopted meets the moment. America cannot adequately defend itself and its vital interests unless it recovers the strategies and instincts that served it well in its greatest triumph of the past century — not World War II, but the Cold War.

The phrase “Cold War mind-set” is usually meant as an insult, sometimes with good reason. Stretches of that long struggle were marked by political paranoia, nuclear brinkmanship and ideological Manichaeism that nobody should want to repeat. There were blunders and fiascos, none greater than the war in Vietnam.

Yet it is worth remembering that our victory in the Cold War didn’t come at a cost of more than one million American casualties, as World War II did. The architects of the Cold War understood that the country’s future security required engagement, not isolation, and that the primary purpose of military power was the prevention of war through deterrence, alliances and international legitimacy — hence the name the Department of Defense, not War.

America’s Cold War strategists also knew that previous concepts of security were inadequate in an era of long-range bombers and intercontinental ballistic missiles. A return to isolationism was the road to a second Pearl Harbor.

They knew that the United States could not hope to win an ideological struggle against Communist adversaries if we were faithless to our own ideals. Among the reasons that President Harry Truman desegregated the armed forces was that the United States could hardly offer itself as a model of freedom and justice while enforcing racist policies in the ranks of those we sent around the world to advance those values.

They knew that deterring the Soviet Union required preserving America’s scientific and technological edge, which in turn called for national investments in research and development and partnerships with American universities. The first modern computer, ENIAC, was developed for the Army at the University of Pennsylvania; the Tomahawk cruise missile was largely developed by Johns Hopkins’s Applied Physics Lab.

They knew that the only enduring form of world leadership came through voluntary followership. Moscow had to coerce Poland, Czechoslovakia, Hungary and other satellites into membership in the Warsaw Pact; their restiveness was the Soviet Union’s undoing. Washington’s key allies, by contrast, mostly chose to be on our side.

And they knew that shared prosperity was vital to democratic credibility. The people who created the institutions of the postwar world said that they were binding people together economically so that they would stop fighting with one another. It was an explicit rationale for lowering trade barriers, and it worked. We won the Cold War because the lights were brighter on this side of the wall.

None of this is to ignore the furious policy debates of the Cold War. Yet what’s striking about the era is the broad continuity of policy between Republican and Democratic administrations. Dwight Eisenhower adopted the containment policies bequeathed to him by Truman. Richard Nixon embraced the logic of arms control and détente that he inherited from John F. Kennedy and Lyndon Johnson. Ronald Reagan expanded the defense buildup started under Jimmy Carter. Continuity meant predictability, and predictability helped maintain peace.

This is not the approach of the Trump administration. Mr. Trump believes in cutting deals, not sharing values; in making money, not winning friends. He has waged a funding war against basic research at our leading universities. And he is infatuated with displays of hard power — the power to coerce, in the formulation of the political scientist Joseph Nye — but contemptuous of the value of soft power, which is the power to attract. His latest National Security Strategy, released this month, is notable mainly for its indifference to the distinction between despotism and democracy.

His approach is inadequate for the long-term challenge America faces. A country’s military is only as good as the purpose to which it is harnessed. And the central purpose of American power should be to defend political liberty and the rule of law that undergirds it, against all enemies foreign and domestic.

That mission may be impossible for an administration whose defining trait is the assault on the rule of law, which is as much a foreign-policy crisis as it is a domestic one. The United States cannot lead the free world, inspire those who want to be a part of it, or oppose those who seek to undermine and destroy it if we cease to be a model democracy ourselves.

What of future presidents? Mr. Trump’s presence in the White House does not erase the reality that Russia seeks to annex one neighbor and probably others. Or that China is eyeing regional hegemony in the Indo-Pacific while it rapidly expands its conventional and nuclear arsenals. Or that America remains threatened by extremist groups that can use A.I., drones, bioweapons or other increasingly ubiquitous and inexpensive technologies to perpetrate future Sept. 11-type attacks.

The horrors that China has visited on the Uyghurs and Russia has imposed on Ukrainians are not only a sign of the immoral core of these regimes; they are also the portents of violent instability to come. A Chinese attack on Taiwan that ends up disrupting or destroying that island’s chip foundries would push the world into an economic crisis. A Russian attack on even a small NATO member state, such as Estonia, would put Europe and America alike on a global war footing.

All this strikingly resembles the challenge America and our allies faced from the Soviet Union at the outset of the Cold War: a contest both ideological and military, requiring a response equal to both. After World War II, the United States met the threat of Russian arms with military investments that yielded some of the most transformative technologies of the century: supersonic aircraft, nuclear-powered submarines, thermonuclear weapons, guided missiles, satellite reconnaissance. They were essential in dissuading Soviet leaders from doing to Western Europe what Vladimir Putin is doing to Ukraine. America must pursue today’s military innovation with equal resolve.

But arsenals alone did not win the Cold War. Just as important were the tools of soft power. Respectful consultation among allies. Mutually beneficial trading ties. Fidelity to democratic ideals. A willingness to face and overcome the moral hypocrisies of democratic states. Strategic firmness matched with diplomatic flexibility toward our foes.

In the end, the power of our military deterrent and the resilience of our global alliances in the 20th century buttressed the most important weapon in the struggle against totalitarianism: patience. From one president to the next, America’s leaders waited out authoritarian challengers until they came apart on their own internal contradictions. The Cold War ended in Berlin, of all places, because ordinary people in the eastern half of the city yearned for a better life in an open society, just over the barbed wire on the other side of the wall.

If the United States is indeed on the cusp of a new Cold War with authoritarian adversaries, these will be the tools we will require to get through another long struggle. We cannot afford the consequences of a world in which dictators can aggress at will, as they did before World War II, and as they have started to do again. Preventing that requires a military that has the right tools, the right tactics and the right culture. It requires a global alliance of like-minded democracies. Most of all, it requires leaders with the wisdom and vision to explain the stakes and rally the free world to the work ahead.