Touting President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE’s first trip overseas as president as “historic” and “unprecedented,” a senior White House official said Saturday that “this trip has left no one with any doubt about who America’s friends are.”

The president arrived back at the White House on Saturday night after a nine-day trip overseas. He made many stops, among them Saudi Arabia, Israel, the Vatican, Belgium and Italy. The administration official told reporters aboard Air Force One on the trip back to the U.S. that the trip clarified Trump's position to U.S. allies.

“People didn’t feel like they knew where America stood, they didn’t feel like they knew who America’s friends were, who America’s foes were,” he said. ADVERTISEMENT In Saudi Arabia, the president's first stop abroad, Trump secured a massive arms sale, worth about $110 billion. In Jerusalem, he shored up the United States' relationship with Israel and reaffirmed his commitment to Middle East peacemaking. In Brussels, Trump ratcheted up his call for NATO members to bolster their defense spending in order to meet their treaty obligations.

However Trump did not reaffirm the United States' commitment to mutual defense during an address to NATO leaders because it "went without saying," a senior administration official said Saturday.

“You have to believe me when I tell you … that the first time any of us ever thought about the issue of putting in a reaffirmation was when we got inquiries about it after the speech," the official told reporters aboard Air Force One.

"It was just not ever something that we even considered we would be asked about because it goes without saying," the official added.

During a speech at NATO headquarters in Brussels on Thursday, Trump urged fellow leaders to spend at least two percent of their GDP on defense, an agreement reached by the alliance in 2014, arguing that the U.S. was bearing an unfair burden.

But notably absent from the president's address was an affirmation that the U.S. would stick to the principle of mutual defense, a key provision in the NATO charter

As a presidential candidate, Trump berated NATO as an "obsolete" organization, though he reversed that position last month after meeting with NATO Secretary-General Jens Stoltenberg.

Still, that Trump did not pledge support for mutual defense reportedly irked some NATO members, who have grown increasingly wary of potential Russian aggression in Europe.