A NATO summit designed to please President Trump ended on Wednesday with his European allies approving an ambitious spending goal to meet the threat of a militarizing Russia, and clinching a long-elusive public commitment from the mercurial American leader for the alliance’s collective defense.

Since his first term, Mr. Trump has been pressing for the allies to spend more on their own defense. On Wednesday, after a one-day meeting in the Netherlands, they agreed to raise their spending on the military to 5 percent of their national income by 2035.

That amount consists of 3.5 percent on traditional military needs like troops, weapons, shells and missiles, up sharply from the current target of 2 percent. It also include another 1.5 percent on “militarily adjacent” projects like improved roads and bridges, better emergency health care, better cybersecurity and civic resilience.

Mr. Trump was pleased.

“This was a tremendous summit, and I enjoyed it very much,” he said at a news conference at the end of the meeting. He added that he understood the central role the United States plays in the defense of Europe. “They want to protect their country, and they need the United States and without the United States, it’s not going to be the same,” he said.

Mr. Trump has long denigrated NATO allies as freeloaders, relying on the United States for protection, and Vice President JD Vance and Defense Secretary Pete Hegseth have described Europe as a drain on American security resources. The president has even mused publicly about withdrawing from the alliance.

But the summit’s brief communiqué, unanimously approved on Wednesday, included a restatement of the allies’ commitment to collective defense in Article 5 of the NATO pact. The president has often been reluctant to commit publicly to Article Five, though he often does in private.