ANALYSIS | For Donald Trump, it’s all personal. But British Prime Minister Theresa May showed him that might not be enough.

During his first joint press conference with a foreign leader, it became clear that American foreign policy will be, in part, driven by how the former real estate mogul and businessman feels about his counterparts.

Trump, who has never held another political office at any level, referring to May, alluded to “the relationship that we’ve developed … just by being with each other” for about an hour Friday at the White House. For Trump, business transactions, in large part, come down to personal relationships. And, he suggested, if he can just develop one with Russian President Vladimir Putin, U.S.-Moscow relations will vastly improve.

“But we look to have a great relationship with all countries, ideally. That won’t necessarily happen, unfortunately probably won’t happen with many countries,” he said. He used his private meeting and an afternoon working lunch with May as an example of how his personal relationship-building can improve America’s dealings with other nations. “But if we can have a great relationship with Russia and with China and with all countries, I’m all for that,” he said. “That would be a tremendous asset.”

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The diplomat in chief vowed to represent the American people “very, very strongly — very forcefully.” But what came into sharper focus Friday was America’s relationships for the next four years likely will hinge on Trump’s relationships with the individuals who lead other countries.

BBC’s cameras even caught Trump taking May’s hand as they walked from the Oval Office into another part of the White House. They held hands for a few seconds in a glimpse of Trump’s interpersonal approach.

“And if we have a great relationship with Russia and other countries, and if we go after ISIS together … I will consider that a good thing, not a bad thing,” he told reporters. “How the relationship works out, I won’t be able to tell you that [until] later. I’ve had many times where I thought I’d get along with people and I don’t like them at all.

“And I’ve had some where I didn’t think I was going to have much of a relationship and it turned out to be a great relationship,” Trump said in a telling moment.

But whether Trump’s relationship with May will influence her decision-making remains unclear. She appeared to try and box him on several issues.

For instance, May showed she is no rookie politician when she revealed Trump’s private remarks to her about NATO, a European-U.S. military alliance he called “obsolete” as a candidate.

“On defense and security cooperation, we are united in our recognition of NATO as the bulwark of our collective defense, and today we’ve reaffirmed our unshakable commitment to this alliance,” May said.

“Mr. President, I think you said, you confirmed that you’re 100 percent behind NATO,” she said, turning to face the American president. “But we’re also discussing the importance of NATO continuing to ensure it is as equipped to fight terrorism and cyber warfare as it is to fight more conventional forms of war.”

“That’s true,” Trump replied softly, and off mic.

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May appeared to school Trump again when answering a question about whether he plans to lift sanctions on Russia.

After the U.S. commander in chief said it is too early in his presidency to say whether he will lift or keep in place the sanctions on Moscow, May again pounced.

“We have, as far as the U.K. is concerned on sanctions for Russia in relation to their activities in the Ukraine, we have been very clear that we want to see the Minsk Agreement fully implemented,” she said. “We believe the sanctions should continue until we see that Minsk Agreement fully implemented and we’ve been continuing to argue that inside the European Union.”

Still, Trump appeared in no mood to describe his Russian policy. After all, he says he hasn’t met Putin yet, although he has previously claimed to have met him. On this, PolitFact last year gave him its “Full Flop” ruling for claiming both to have met him and not met him.

“As far as, again, Putin and Russia, I don’t say good, bad or indifferent,” he said. “I don’t know the gentleman. I hope we have a fantastic relationship. That’s possible and it’s also possible that we won’t. We will see what happens.”

Contact Bennett at johnbennett@cqrollcall.com. Follow him on Twitter @BennettJohnT.