Of NATO, where the U.S. underwrites three-fourths of the cost of defending Europe, Trump calls this arrangement "unfair, economically, to us," and adds, "We will not be ripped off anymore."
Beltway media may be transfixed with Twitter wars over wives and alleged infidelities. But the ideas Trump aired should ignite a national debate over U.S. overseas commitments -- especially NATO.
For the Donald's ideas are not lacking for authoritative support.
The first NATO supreme commander, Gen. Eisenhower, said in February 1951 of the alliance: "If in 10 years, all American troops stationed in Europe for national defense purposes have not been returned to the United States, then this whole project will have failed."
As JFK biographer Richard Reeves relates, President Eisenhower, a decade later, admonished the president-elect on NATO.
"Eisenhower told his successor it was time to start bringing the troops home from Europe. 'America is carrying far more than her share of free world defense,' he said. It was time for other nations of NATO to take on more of the costs of their own defense."
No Cold War president followed Ike's counsel.
But when the Cold War ended with the collapse of the Soviet Empire, the dissolution of the Warsaw Pact, and the breakup of the Soviet Union into 15 nations, a new debate erupted.
The conservative coalition that had united in the Cold War fractured. Some of us argued that when the Russian troops went home from Europe, the American troops should come home from Europe.
Time for a populous prosperous Europe to start defending itself.
Instead, Bill Clinton and George W. Bush began handing out NATO memberships, i.e., war guarantees, to all ex-Warsaw Pact nations and even Baltic republics that had been part of the Soviet Union.
In a historically provocative act, the U.S. moved its "red line" for war with Russia from the Elbe River in Germany to the Estonian-Russian border, a few miles from St. Petersburg.
We declared to the world that should Russia seek to restore its hegemony over any part of its old empire in Europe, she would be at war with the United States.
No Cold War president ever considered issuing a war guarantee of this magnitude, putting our homeland at risk of nuclear war, to defend Latvia and Estonia.
Recall. Ike did not intervene to save the Hungarian freedom fighters in 1956. Lyndon Johnson did not lift a hand to save the Czechs, when Warsaw Pact armies crushed "Prague Spring" in 1968. Reagan refused to intervene when Gen. Wojciech Jaruzelski, on Moscow's orders, smashed Solidarity in 1981.
These presidents put America first. All would have rejoiced in the liberation of Eastern Europe. But none would have committed us to war with a nuclear-armed nation like Russia to guarantee it.
Yet, here was George W. Bush declaring that any Russian move against Latvia or Estonia meant war with the United States. John McCain wanted to extend U.S. war guarantees to Georgia and Ukraine.
This was madness born of hubris. And among those who warned against moving NATO onto Russia's front porch was America's greatest geostrategist, the author of containment, George Kennan:
"Expanding NATO would be the most fateful error of American policy in the post-Cold War era. Such a decision may be expected to impel Russian foreign policy in directions decidedly not to our liking."
Kennan was proven right. By refusing to treat Russia as we treated other nations that repudiated Leninism, we created the Russia we feared, a rearming nation bristling with resentment.
The Russian people, having extended a hand in friendship and seen it slapped away, cheered the ouster of the accommodating Boris Yeltsin and the arrival of an autocratic strong man who would make Russia respected again. We ourselves prepared the path for Vladimir Putin.
While Trump is focusing on how America is bearing too much of the cost of defending Europe, it is the risks we are taking that are paramount, risks no Cold War president ever dared to take.
Why should America fight Russia over who rules in the Baltic States or Romania and Bulgaria? When did the sovereignty of these nations become interests so vital we would risk a military clash with Moscow that could escalate into nuclear war? Why are we still committed to fight for scores of nations on five continents?
Trump is challenging the mindset of a foreign policy elite whose thinking is frozen in a world that disappeared around 1991.
He is suggesting a new foreign policy where the United States is committed to war only when are attacked or U.S. vital interests are imperiled. And when we agree to defend other nations, they will bear a full share of the cost of their own defense. The era of the free rider is over.
Trump's phrase, "America First!" has a nice ring to it.