NATO leaders agreed on Wednesday to a goal of spending 5 percent of their gross domestic product on defense. But that doesn’t mean each member nation will actually spend that much.

The difference lies in a bit of mushy diplomatic language that lets the NATO secretary general, Mark Rutte, claim that he delivered on President Trump’s spending demand. The brief and unanimously approved communiqué that NATO issued after leaders wrapped up their annual summit says that “allies” — not “all allies” — had agreed to the 5 percent figure.

“Most of them, I guess almost all of them, are going to be contributing now 5 percent,” Mr. Trump said.

But he lashed out at Spain, whose leaders had pushed for the wiggle room in the wording to avoid committing to the spending target. Spain spends about 1.28 percent of G.D.P. on defense, according to the most recent official figures available.

“Spain is terrible, what they’ve done,” Mr. Trump said. He added, “We’re negotiating with Spain on a trade deal; we’re going to make them pay twice as much. I’m actually serious about that.”

The tweaked language in the communiqué was the result of a compromise struck between Mr. Rutte and Prime Minister Pedro Sánchez of Spain to gloss over the dispute and project unity at the short summit, held in The Hague.