George Papadopouolos used Twitter Monday night to start attacking Australian politician and diplomat Alexander Downer, whose response was "I'll leave others to make judgments about the veracity of those tweets".
Papadopoulos and Downer met for drinks in London in May 2016, and at the meeting, Papadopoulos told Downer the Russians had damaging information on Hillary Clinton.
Downer reportedly relayed this information to Australian authorities, who then passed it along to their American counterparts, leading the FBI to open a counterintelligence investigation into the Trump campaign.
This inquiry would later be folded into the ongoing investigation by special counsel Robert Mueller.
The former Trump campaign adviser, who reportedly sparked an FBI investigation into potential Russian collusion between Trump campaign and the Russian government, strongly implied in his tweets that, contrary to news reports, he never told Downer that Russia had obtained a trove of Hillary Clinton's emails.
Papadopoulos wrote that Downer had wanted to meet him in London under "incredibly suspicious circumstances".
Papadopoulos, who received a sentence of 14-days in jail, a year of supervision, 200 hours of community service, and a $9500 fine on Friday, seems to be adopting an aggressive and defiant stance against the Mueller investigation.
Papadopoulos wrote that Downer had wanted to meet him in London under "incredibly suspicious circumstances".
"I found it so odd that Downer, who gained notoriety in Australia for wearing women's fish nets, invited me to 'order' me to stop 'bothering' his good friend David Cameron," Papadopoulos said in a subsequent tweet.
"And told me my views were hostile to British interests."
(Downer famously posed in fishnet stockings in 1996 for charity.)
In subsequent tweets Papadopoulos suggested Downer was close to the Clintons.
"So basically, for those paying attention, we have a Clinton friend, connected to the MI6, and private intelligence organisations in London, probing me about my ties to the energy business offshore Israel," he wrote. "Nothing about the US-Australia relationship.
"Yet I supposedly told THAT individual about emails. Something I have no recollection ever discussing."
A few hours later he tweeted: "The notion that Downer randomly reached out to me just to have a gin and tonic is laughable.
"Some organisation or entity sent him to meet me.
"For the sake of our republic and the integrity of this investigation, I think it's time Downer is as exposed as Christoper [sic] Steele.
"Would be a very very big problem if British intelligence was weopanized [sic] against an American citizen."
In a recent interview with The New York Times Papadopoulos said he had told the Greek foreign minister that Russia had obtained Clinton campaign emails.
But he said he did not recall mentioning this to Downer and insisted he did not communicate it to other officials in the Trump campaign, even though it would have been extremely valuable information.
Downer dismisses Twitter rant from ex-Trump adviser, sentenced for lying (Sydney Morning Herald)