Despite sometimes promiscuous claims by President Trump’s critics, controversy about America’s commitment under Article 5 dates back seven decades. If largely quiescent through the Soviet Union’s collapse, it was because the core Article 5 commitment thankfully went untested. Controversy reemerged with NATO enlargement eastward. In a strange inversion, what c.1949 was a prime objection to its commitment to use force—what Senator Forrest Donnell called the illusory discretion of the “such action as it deems necessary” condition added by George Kennan and other proponents to rescue the Washington Treaty in the Senate—is now embraced, ahistorically, by Article 5 hawks: that the commitment is mechanical, not discretionary. It is substantially a unilateral American one, too. Chronic European underspending and anemic public support across the continent challenge whether most NATO countries could—or would—rally to an ally’s defense.