(CNN) President Donald Trump plans to meet one-on-one with Vladimir Putin at the start of their July 16 summit in Helsinki, Finland, according to a person familiar with the plans, before allowing other aides to join the highly anticipated encounter with the Russian leader.

The meeting will be the first formal summit talks between them. They have met previously on the sidelines of conferences.

Trump has shown an affinity for meeting individually with his counterparts before opening the room to fuller delegations. During his historic summit with Kim Jong Un last month, Trump met for about an hour with just the North Korean dictator, joined only by their translators. Emerging from the face-to-face, Trump told reporters the discussion was "very, very good."

He had said before the Singapore talks that he wanted to take the measure of Kim personally and gauge their chemistry. In the case of Putin, Trump has already assessed their interpersonal ties up close, but wants more time to develop the leader-to-leader relationship, according to the person familiar with the summit's planning.

Ahead of the North Korea summit, some US officials expressed concern about a meeting without any other aides present. Without official note-takers or other witnesses, one-on-one meetings lack any official record, making it difficult afterward to determine whether agreements have been reached. Putin is known as a shrewd negotiator who some officials worry could exploit such a session and extract concessions from Trump.

At Trump and Putin's first meeting , on the margins of the G20 summit in Hamburg, Germany, a year ago, the only aide to accompany the President was then-Secretary of State Rex Tillerson, along with a US translator. The session went so long that first lady Melania Trump was sent in to try to cut it off.

In a second conversation during dinner at the same summit, Trump was without a translator who spoke Russian, so instead relied on Putin's. The men spoke for about an hour without any other aides present, officials said later. The White House downplayed the significance of the encounter, but experts expressed concern there was no official US record of the talk.

This time, it's expected a larger delegation of aides will participate in the expanded portion of the summit for a discussion that will center on Syria, nuclear weapons and election meddling.

"The goal of this meeting really is for the two leaders to have a chance to sit down, not in the context of some larger multilateral meeting, but just the two of them, to go over what is on their mind about a whole range of issues," national security adviser John Bolton said Sunday on CBS's "Face the Nation."

Will Trump press Putin on election meddling?

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Bolton said the issue of election meddling would arise, despite Putin's denials that Moscow attempted to sway the 2016 US presidential contest. Trump himself cited that denial last week in a tweet, at the same time posing questions about why the FBI did not investigate Hillary Clinton's ties to Russia.

Trump raised the meddling issue during his first meeting with Putin in Hamburg. But afterward, differences emerged between the two sides. Tillerson said Trump had pressed Putin on the matter. But the Kremlin said Trump had accepted Putin's denials that Russia interfered in the election.

In a conversation with reporters aboard Air Force One on Friday, Trump indicated the election issue would arise again, along with other matters.

"I'll talk to him about everything," Trump said. "We're going to talk about Ukraine, we're going to be talking about Syria, we'll be talking about elections. And we don't want anybody tampering with elections. We'll be talking about world events. We'll be talking about peace. Maybe we talk about saving billions of dollars on weapons, and maybe we don't."

That, according to aides, was a reference to Trump's long-standing interest in addressing what he perceives as a potential nuclear arms race between the US and Russia. Earlier this year, Putin boasted about the strength of Russia's arsenal, to which Trump took umbrage . He raised that issue in his last phone call with Putin, which occurred in March, and hopes to raise it again during the July 16 talks. He has told advisers that any face-to-face meeting with the leader of a nuclear power -- including Putin and Kim -- is a worthwhile endeavor.

Trump wants grand event

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Trump is expected to begin formal preparations for the Putin meeting in the coming days, according to aides. That's likely to include brief sessions with Bolton and Secretary of State Mike Pompeo, along with other national security officials.

Ahead of his Hamburg meeting with Putin -- to date, their only formal sit-down -- Trump was presented with a briefing binder that also included pages on his other bilateral sessions during the G20. The section on his meeting with Putin amounted to only a "few pages," according to one White House official. A second official said the documents included talking points, each only a sentence or two long, to keep Trump focused during his meeting.

It's not clear yet what other events Trump and Putin have planned for their summit in Helsinki. The Kremlin has suggested the leaders would deliver statements to the media, though the White House has yet to lay out similar details.

Trump has told planners he wants the event to feel monumental, in the style of previous summit meetings between US and Russian leaders. Helsinki was selected in part to lend the event historical weight, people familiar with the matter said. The Finnish capital hosted summits between President George H.W. Bush and Soviet leader Mikhail Gorbachev, and President Bill Clinton and Russian President Boris Yeltsin.

Already, some of Trump's critics are warning against an overly friendly meeting with Putin, particularly as Trump picks trade battles with longtime US allies . A NATO meeting ahead of the Putin summit is expected to be contentious as Trump presses members of the alliance to increase their defense spending.

On Monday, leading foreign-policy Democrats urged Trump in a letter to hold Putin accountable for Russia's destabilization efforts, including election meddling, support for the Syrian regime and the annexation of Crimea.

"While there is a place for dialogue between nations on disagreements and common challenges, such as reducing nuclear dangers, we are deeply concerned that your Administration continues to send mixed messages regarding the Russian security threat," the Democrats -- Sens. Robert Menendez of New Jersey, Dick Durbin of Illinois, Mark Warner of Virginia and Jack Reed of Rhode Island -- wrote to Trump. "During your meeting with President Putin, we ask that you convey that there will be clear consequences for Russia's interference in democratic processes in the United States and elsewhere, its support for violence and bloodshed in Ukraine and Syria, and the illegal occupation of Crimea."