Donald Trump is now the presidential candidate of the Republican Party, with a significant chance to be the next president of the United States. He promises that, if he is elected, America will stop "losing" and become "great" once again. In his hands, one supposes, the world will be our oyster.

But Trump is short on specifics as to what strategy and tactics will make us great. Does he know? Can he learn? From whom?

As Trump himself noted in his recent foreign-policy speech, we Americans actually won both World War II and the Cold War, and by winning those struggles we became great on the world stage. We feel we have become "small" through losing in Vietnam, Iraq and Afghanistan.

Trump proposes to "Make America Great Again" by pulling us out of NATO and renting out our military forces to those who will pay to hire them. He similarly proposes to make us "great" essentially by pulling us out of the world economy with high tariffs and trade wars.

All this will only raise the cost of goods for all Americans and make us "small" in the long view of world history.

And Trump is not alone. Bernie Sanders is with him in opposing free trade and, echoing the 1962 Port Huron Statement from the activist movement Students for a Democratic Society, in attacking Hillary Clinton for her support of American "Big Powerism."

Perhaps it would pay to ask: Why and how did we defeat fascism in World War II and communism in the Cold War? What did we do to avoid "losing" in those historic conflicts?

Just over 70 years ago, in March 1946, British Prime Minister Winston Churchill opened the first round of what was soon to become the "Cold War" between communism and capitalism with his "Iron Curtain" speech at Westminster College in Fulton, Mo.

Just two weeks earlier, U.S. diplomat George Kennan, then posted to Moscow, had sent back to Washington his famous "Long Telegram" concluding that the Soviet Union was embarked on a course of ideological conquest seeking the communist domination of free societies everywhere. The U.S., he argued, must oppose such aggression through the techniques of a "cold" war that would last a long time.

In 1989, as predicted by Churchill and Kennan and by using their strategic recommendations, the U.S. and its allies prevailed in the Cold War with the fall of the Berlin Wall and the liberation of Eastern Europe.

A few years later the Soviet Union itself collapsed.

The American people played an exceptional role in human history during the Cold War, as they had in World War II. Twice they defeated evil powers and won the day for human dignity.

But the insightful strategic vision of Kennan and Churchill is not being applied in our current "cold" war against a globalizing movement — this time a foe advancing an uncompromising totalitarian perversion of Islamic teachings. If we want to prevent America from becoming "small," we should learn from history and recall with appreciation what Kennan and Churchill recommended 70 years ago.

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Kennan saw that Soviet policy was to miss no opportunity to "reduce strength and influence, collectively as well as individually of capitalist powers" in a "relentless battle." He saw that the Soviets would "utilize to the maximum democratic-progressive elements to bear on capitalist governments along lines agreeable to Soviet interests." He saw that Soviet efforts would take place both in the official realm and also in the "subterranean" realm of subversion — that the Soviets would focus on European colonies to create vacuums of power there into which communist-Soviet penetration would be successful with no holds barred. And he saw that there would be no cultural collaboration with capitalist powers.

According to Kennan, the Soviets would seek to "disrupt national self-confidence, hamstring measures of self-defense, increase social and industrial unrest, stimulate all forms of disunity [and] urge those with economic and racial grievances towards violent struggle for the destruction of other elements in their societies."

"The poor," he wrote, "will be set against the rich, black against white, young against old, etc."

World communism, Kennan wrote, "is like malignant parasite which feeds only on diseased tissue."

Communism would work to undermine all forms of personal independence — economic, political or moral. "Their system can handle only individuals who have been brought into complete dependence on higher power," Kennan said.

He concluded that the problem of the Soviets was probably "the greatest task … our diplomacy will ever have to face" but that the problem was within our power to solve, without recourse to any general military conflict. We could defeat Soviet efforts by fighting a "cold" war.

Kennan thought the Soviets would not challenge superior power. The American strategy, therefore, had to be defensive and look to building up and maintaining capacities all around the world to block and deter Soviet machinations of every kind.

We needed to "formulate and put forward for other nations a much more positive and constructive picture of the sort of world we would like to see than we have put forward in past."

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Churchill spoke similarly in his legendary address in Missouri. He described the challenge: tyranny — all-embracing police-state governments where the power of the state is exercised without restraint.

He proposed that the United States and the United Kingdom stand together, with others, to demand for the people of every country the right to free, unfettered elections, freedom of speech and thought, and the rule of law.

His recommended overall strategic concept was care for the "safety and welfare, freedom and progress, of all the homes and families of all the men and women in all the lands."

He memorably described how "an iron curtain" had descended across the European continent and that communist parties or fifth columns constituted a growing challenge and peril to Christian civilization.

He said that no one knew the limits, if any, to the expansive and proselytizing tendencies of Soviet Russia.

But Churchill believed that Russia did not want war, only "the fruits of war and the indefinite expansion of their power and doctrines."

The U.S. and the U.K., he advised, should "walk forward in sedate and sober strength seeking no one's land or treasure, seeking to lay no arbitrary control upon the thoughts of men."

The global ambitions of Soviet Communism were to be held in check, said Churchill, not by fighting but by deliberate accumulation of "constancy of mind, persistency of purpose, and the grand simplicity of decision," all dedicated to advancement of democracy and freedom.

Looking back now from our vantage point across 70 years of lived history, two conclusions stand out: First, that Kennan and Churchill were right about Soviet communism; and, second, that their advice was sound as to how to defeat totalitarian imperialism.

Communism was defeated mostly by fighting a "cold" war of ideas, keeping up strong physical defenses and promoting global economic development.

The two exceptions to the general strategy of waging only "cold" war were the bloody, costly and controversial local conflicts America fought to defend South Korea and South Vietnam against communist aggression.

Since 9/11, the same civilization that successfully fought off communism has been fitfully waging another "cold" war, one President George W. Bush labeled the "war on terror."

This cold war, too, has had hot episodes of military combat, mostly in Iraq and Afghanistan and now in Syria, but with forays to "contain" terrorist cells and the recruitment of cadres expanding all over the world wherever sympathizers can be found.

So far the U.S. and its allies have failed to terminate the terrorism of violent Islamism.

Why?

I would say because, collectively, a younger generation of American national-security planners has forgotten the advice of Kennan and Churchill: how best to use ideas of free thought and the benefits of economic development as the foundation for defeating a wrongheaded ideology while keeping the use of military force only in a supporting role.

In the war on terror, the U.S. has not applied the 1946 strategic vision of Kennan and Churchill: Let there be no cracks in the wall of our determination to, above all, promote free institutions and prosperity for all. And let there be no halfheartedness in our reaching out to embrace those around the world who seek better lives for their families and honesty and decency in their governments, no matter what their religion.

One wonders whether Donald Trump can learn this lesson.

Stephen B. Young, of St. Paul, is global executive director of the Caux Round Table, an international network of business leaders working to promote a moral capitalism.