Trump deemed the summit in The Hague this week a resounding success, while taking aim at Spain's refusal to commit to dramatic spending increases for defense.

Basking in admiration, the president took a victory lap over new spending commitments, while defending U.S. strikes on Iran.

Mr. Trump had been eager to celebrate his success at NATO and revel in the fact that he had conducted an attack that none of his predecessors had dared to launch. His view was backed up by Mark Rutte, the secretary general of the alliance, who wrote Mr. Trump a private message thanking him for his “decisive action” in Iran.