President Trump's national security adviser, John Bolton, will attend a military parade commemorating Ukraine's Independence Day on Friday, one day after he met in Geneva for what were apparently tense talks with his Russian counterpart, Nikolai Patrushev.

Bolton will also meet on Friday with Ukrainian president Petro Poroshenko and Prime Minister Volodymyr Groysman before holding a press conference, an NSC official said.

Top American officials have traditionally participated in the annual ceremonies as a show of U.S. support for Ukraine, which this year celebrates its 27th year of independence from the Soviet Union. Secretary of Defense Jim Mattis visited the country for its celebrations last year and used the occasion to publicly warn Moscow about its military incursions into Ukrainian territory.

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Bolton's visit to Kiev comes on the heels of a five-hour meeting in Geneva with Russia's Patrushev that Bolton said resulted in "considerable progress."

The meeting nonetheless failed to produce a joint statement due to a disagreement about election meddling, which Bolton said he felt was "important to mention" and raised "a number of times."

"We weren't able to reach agreement on that," Bolton said.

In his remarks, Bolton offered what have been scarce details about the issues discussed by President Trump during his two-hour, one-on-one meeting with Russian president Vladimir Putin last month. The fact of his meeting with Patrushev was, Bolton said, one item the presidents had agreed to in their discussion, as part of an effort to work toward restoring diplomatic and other exchanges.

"That was really the broad objective," he said, "we had to take the discussion that the leaders had and try and spread it out and make it more specific and find concrete ways to proceed."

Bolton said he and his counterpart covered an array of topics, including nuclear nonproliferation, arms control, counterterrorism, illegal immigration, cyber-related issues, and "regional issues" including Syria, the broader Middle East, Afghanistan, and Ukraine.

On the issue of arms control – a priority stressed by Moscow since the Helsinki summit – Bolton was inconclusive, telling reporters there were "a number of possibilities" that the United States would need to consider before committing to take any action on an existing nuclear arms reduction treaty called New Start.

"We are very, very early in the process of considering what we are going to do," Bolton said.

He was less equivocal on the issue of election meddling.

"I made it clear that we wouldn't tolerate meddling in 2018 and that we were prepared to take necessary steps to prevent it from happening," he said.

It was a statement that has not yet been delivered with an equivalent level of clarity from President Trump, who has repeatedly cast doubt on Moscow's involvement in 2016 election interference.

The president has instead often allowed for the possibility that other, usually unnamed, actors carried out an influence campaign, although the U.S. intelligence community concluded with high confidence last year that the Russian government, as ordered by Putin, aimed to help then-candidate Trump's electability while damaging the chances of Hillary Clinton.

In an interview he gave as recently as this week, Trump, decrying the ongoing special counsel probe into connections between his presidential campaign and Russia, said the investigation "played right into the Russians' – if it was Russia – they played right into the Russians' hands."