After landslide Republican primary victories, Donald Trump delivered a speech on Wednesday in Washington, D.C., intended to clarify his foreign policy positions. That was needed, because his views on America's role in the world have until now been expressed in tweets, interviews and remarks at rallies that have alarmed nearly every foreign ally of the U.S.

No one's fears are likely to be allayed by this speech, which was clearly worked up by his new campaign advisers and read from a teleprompter. It did not exhibit much grasp of the complexity of the world, understanding of the balance or exercise of power, or even a careful reading of history.

When one has a hammer, everything looks like a nail. And when one's experience is limited to real estate deals, everything looks like a lease negotiation. Hearing Trump describe his approach to foreign relations, one imagines a group of nations sitting at a table with him at its head, rather like a scene from "The Apprentice," with him demanding more money, more troops and policy changes in exchange for American protection, trade and friendship. And if he doesn't get what he wants? "In negotiation, you must be willing to walk," Trump said.

This unilateral approach makes for good television, but this is the real world, in which other nations have agendas, too. Trump says he is "going to be working very closely with our allies in the Muslim world, all of which are at risk from radical Islamic violence." But how will he gain cooperation for his "unpredictable" war on the Islamic State in Iraq and the Levant (ISIL) while enforcing a "pause" that prevents Muslims from entering this country and forcing those living here to register themselves?

How does one "apply leverage on China necessary to rein in North Korea" while slapping a trade-killing tariff on Chinese imports? It's correct that many of our NATO allies aren't paying their agreed-upon share of its costs — but what happens to America's overseas bases if we "walk?"

While trumpeting America's role in winning World War II and the Cold War, Trump simultaneously pronounced that "America First" — the 1930s isolationist theme that he quoted without attribution — "will be the major and overriding theme of my administration." He did not bother to square that with his vow not to "hesitate to deploy military force when there is no alternative." He condemned "nation building," but said he aims to build "regional stability" — without explaining the difference.

Trump decried a shrinking U.S. military and the deterioration of the nuclear arsenal. But he did not say how he would further build up the military — which has a budget this year of nearly $600 billion — while cutting government spending, which he also wants to do. And he seems to be ignorant of the sweeping $1 trillion effort to revitalize the nuclear force that is already underway.

Trump repeatedly states outright falsehoods, often based on wrong assumptions. He's been refuted before on his claim that ISIL is making "millions of dollars a week" by selling Libyan oil. There is zero evidence of that. The nuclear deal with the U.S. and other major powers has not made Iran a "great power," nor has Tehran violated the conditions of that pact, as Trump has said.

Trump says he knows how to negotiate, and to him that seems to mean putting forward maximal positions that he can then walk back. That won't work in foreign policy. Trump did not display any willingness to learn or to correct his past errors. For someone who claims he is ready to lead the free world, that is inexcusable.

FROM AN EDITORIAL IN THE NEW YORK TIMES