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Someone should brief President Donald Trump on the meaning of NATO—not just its value to America’s global presence and security ever since the alliance was formed in 1949 but also, more simply, what the treaty creating it says.

He would then learn that his pique at the NATO allies for not helping him in his war against Iran—his threat to pull out of the alliance, then, a bit less extremely, to withdraw troops from those countries that refused to help him send warplanes to bomb Iran—has no justification whatever.

Most people know about the centerpiece of NATO’s treaty, Article 5, which states, “An armed attack against one or more of them in Europe or North America shall be considered an attack against them all.” But they tend to ignore the words in the middle of that sentence—an armed attack in Europe or North America.

The implication is that the obligation does not apply to attacks outside Europe or North America. In case anyone detects ambiguity in this clause, Article 6, though almost never cited, states the matter explicitly:

For the purpose of Article 5, an armed attack on one or more of the Parties is deemed to include an armed attack:  • on the territory of any of the Parties in Europe or North America … on the territory of Turkey or on the Islands under the jurisdiction of any of the Parties in the North Atlantic area north of the Tropic of Cancer;• on the forces, vessels, or aircraft of any of the Parties, when in or over these territories or any other area in Europe … or........

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