Rinat Akhmetshin, the man of the hour in U.S. political discourse, has a Canadian connection: He is a frequent participant in the Halifax International Security Forum, which is where I met him a couple of years ago.

A naturalized American and pro-Moscow lobbyist, Mr. Akhmetshin confirmed to the Associated Press on Friday that he was at the June 9, 2016, meeting that Donald Trump Jr. and other senior Trump advisers attended in the hope of receiving information from a Russian lawyer to taint Hillary Clinton.

Now, his background in military counter-intelligence work for his native Russia is raising eyebrows, although he denies ever working formally as any kind of spy.

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Read more: New participant at Trump Tower meeting: a Russian-American lobbyist

I met Mr. Akhmetshin at the forum in November, 2015.

We struck up a conversation at the bar in the hotel where the event was being held. We had whisky and exchanged business cards – his tastes running toward the very expensive, and his credentials proclaiming him as the director of an organization called the International Eurasian Institute.

I asked him about what he was doing at the forum and in the United States in general, but he was evasive on those points. The Halifax event was not the kind of place one would expect to meet many Russians.

The security forum was founded by former Conservative defence minister Peter MacKay. With a focus on NATO and continental security, it brings together politicians, senior security bureaucrats and very senior military officers – primarily from Canada and the United States – once a year. Like other reporters, I finagled face time in the wings with people such as Defence Minister Harjit Sajjan, Chief of Defence Staff Jonathan Vance and some retired spy chiefs, among others. The forum makes such conversations possible.

And while I have no idea who else Mr. Akhmetshin had been talking to there, the forum's own online records show he has been attending the event since 2011. The organizers, who select the participants, do not apologize for this.

"We didn't invite Mr. Akhmetshin with any understanding of a formal tie to the government of Russia," Peter Van Praagh, the founding president of the forum, said in an interview on Friday.

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He added that "this is somebody who works on issues related to the former Soviet space. He is right up to date as to what is happening in the Central Asian republics and South Caucasus and Ukraine and Russia itself, and that knowledge is something people are looking for."

That night at the bar, Mr. Akhmetshin and I talked about our respective times in Afghanistan. I spent a few months covering the NATO mission in the late 2000s. Mr. Akhmetshin, in lightly accented English, described how he served as a Russian military officer there in the 1980s.

We debated whether a war there was still worth fighting and, at one point, pulled a recently retired four-star U.S. general into our conversation. The general did not seem happy about that, but he was fair game because he was standing beside us.

A few days after the event, I e-mailed Mr. Akhmetshin thanking him for the conversation, but concluded it by saying: "Tell me what you do, some time."

Mr. Akhmetshin wrote back a few months later, after another Globe and Mail reporter wrote about an anti-Putin activist coming to Ottawa to push for laws punishing Russian human-rights violators.

That visit kick-started a Parliamentary discussion about a possible Canadian version of the U.S. Magnitsky act, named for a Russian lawyer who died in prison after exposing fraud and corruption.

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"I couldn't help but notice that your paper wrote about canadian parliament being lobbied by ex-american banker to bring additional sanctions against Russia," his e-mail said.

Mr. Akhmetshin urged that The Globe and Mail investigate the anti-Putin activist's story instead, claiming key details might be untrue.

I never followed up on that suggestion.