And according to one report, Trump told the G7 leaders in Quebec last month that Crimea should “probably belong to Russia because everyone there speaks Russian”.

Asked by reporters on Saturday Trump said “we’re going to have to see” about the Crimea question, and “I’ll talk to [Putin] about everything”.

National Security Adviser John Bolton, who met with Putin in Moscow last week, said the US position on Crimea being part of Ukraine was clear, but added “the President makes the policy”.

On Monday White House spokeswoman Sarah Sanders said the US continued to reject Russia’s annexation of Crimea, and the US sanctions imposed on Moscow following the 2014 annexation would “remain in place until Russia returns the peninsula to the Ukraine”.

Russia has said it is not interested in discussing the status of Crimea except as “an inseparable part of Russia”.

But Trump said he intended to talk to Putin about Ukraine, as well as Syria and “elections, we don’t want anybody tampering with elections”.

Halper-Hayes said Trump was “not interested in making a deal” with Putin.

“He’s interested in meeting him face to face, he’s interested in saying ‘you’d better not interfere in our elections’.

“He’s going to want to come out saying that he and Putin are buddies and he’s just going to upset so many people that he’s going to be positive about Putin because Putin is also one of our greatest enemies.”

But she said not to assume the public comments represented what took place inside the meeting.

The world should not expect “some great resolution”, she said.

“No, he is into building a relationship. He builds relationships, that has always been very important to him.”

Though Trump has long-standing objectives with Russia, the meeting would not be closely scripted.

“He’ll figure out what to bring up,” Halper-Hayes said.

According to media reports, Trump wants a one-on-one meeting with Putin without any note-takers to create an official record, or aides to help steer the conversation.

Moscow has indicated Putin is open to a private meeting between the two before the summit officially begins on July 16.

Kremlin spokesman Dimitry Peskov said on Tuesday the Russian leader “feels absolutely comfortable in all formats that are comfortable for his interlocutors”.

US Secretary of State Mike Pompeo spoke with Russian Foreign Minister Sergey Lavrov on Tuesday, according to a short note issued by his department, and they discussed the Trump-Putin meeting, as well as Syria and North Korea.

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Halper-Hayes, who is a psychologist, said she had heard people say Trump’s opinion “changes based on the last person he’s talked to” and though she did not think it true “there are times I get wobbly about that”.

“But he really isn’t being fooled,” she said.

Halper-Hayes said Trump does not read a lot and “needs to get information verbally”, but she said he “absorbs an enormous amount”.

On the subject of Trump’s regular false statements on social media and elsewhere, Halper-Hayes said he was a “marketing guy” and a “grand embellisher” and admitted “I really don’t understand why he contradicts himself”.

Part of it was always wanting to be the biggest and best, she said – a result of his New York upbringing.

Trump is “purposefully, predictably unpredictable”, Halper-Hayes said.

“He is a problem solver and he’s action oriented. You’re not going to get a foreign relations pontification or philosophy. There are problems [and] he wants to deal with them.”