President Donald Trump continues to cast doubt on US intelligence assessments that Russia meddled in the 2016 presidential contest, just as his aides are finalizing details of his upcoming summit talks with President Vladimir Putin.

“Russia continues to say they had nothing to do with Meddling in our Election!” Trump wrote on Twitter Thursday morning. He went on to question why US law enforcement agencies weren't investigating other perceived influences on the election, which he has repeatedly said was rigged for his opponent Hillary Clinton.

“Where is the DNC Server, and why didn't Shady James Comey and the now disgraced FBI agents take and closely examine it? Why isn't Hillary/Russia being looked at? So many questions, so much corruption!” he wrote.

The President's tweet was sent roughly a half hour before the White House announced that the two leaders will meet on July 16 in Helsinki, Finland, where they will “discuss relations between the United States and Russia and a range of national security issues.”

Trump's summit with Putin is likely to draw criticism from the US President's domestic critics, who accuse him of currying favor with Putin, and jitter US allies, who fear Trump will take a less hawkish position with Russia on issues such as the annexation of Crimea and military exercises near the Russian border in eastern Europe.

The summit takes place four days after a NATO meeting in Brussels, Belgium, where Trump will meet leaders of US military allies. NATO members were worried that if the summit with Putin had taken place earlier, Trump might have agreed to something with the Russian leader that they would have been forced to go along with.

Speaking in Moscow on Wednesday, US national security adviser John Bolton said Trump would likely raise the election meddling issue during his sit-down with Putin. Bolton himself addressed it during his own meeting with Putin this week.

And he brushed aside suggestions that a Trump-Putin meeting would amount to conciliation from a President who intelligence agencies assess was favored by the Russian government.

“I think a lot of people have said or implied over time that a meeting between President Trump and President Putin somehow proves some nexus between the Trump campaign and the Kremlin, which is complete nonsense,” Bolton said in Moscow.

Trump himself has been committal. Asked in the Oval Office on Wednesday whether election meddling would arise in his talks with Putin, Trump turned to his Portuguese counterpart and said: “You never know with meetings, right? But I think a lot of good things can come from meetings with people.”

US intelligence agencies concluded in a January 2017 report that Russia sought to influence the presidential election in Trump's favor. “We further assess Putin and the Russian Government developed a clear preference for President-elect Trump,” the report read.

Two agencies – the CIA and the FBI – came to that assessment with “high confidence.” Another, the National Security Agency, arrived at that conclusion with “moderate confidence.” Trump has downplayed those conclusions previously, saying he takes Putin at his word when he says Moscow did not attempt to influence the election.

“He said he didn't meddle. He said he didn't meddle. I asked him again. You can only ask so many times,” Trump told reporters in November, shortly after speaking with Putin on the sidelines of a leaders summit in Vietnam.