The head of Canada’s intelligence and security agency said he has a "different explanation" for an alleged error in an intelligence briefing cited by the Prime Minister's Chief of Staff during her testimony at the foreign interference inquiry.

Katie Telford, who has served as Chief of Staff to Prime Minister Justin Trudeau since 2015, told the inquiry committee in April that the Canadian Security Intelligence Service (CSIS) raised a red flag about a "threat connected to a parliamentary member" that "does not seem to be true."

She testified, "And the officials involved should be credited for going and working through the night and coming to us the next day and reversing their assessment because they made a mistake in how they interpreted the information."

Telford said this experience taught the Prime Minister's Office (PMO) to have no "initial confidence" in CSIS information.

During a recent interview with CBC News, CSIS Director David Vigneault carefully challenged Telford’s account of events.

He said, "I may have a different explanation for this particular event referenced in the testimony."

Vigneault did not delve into details, but he stated that there is a difference between making a mistake and reassessing an intelligence report.

He added, "Intelligence is like building a puzzle. Sometimes, you're at the beginning of the puzzle, and you're not really sure how it all fits together, and that's how your intelligence comes out; sometimes, when you have more pieces of the puzzle, you can be more precise in your assessment."

Vigneault said the intelligence and security management can do a better job explaining this distinction to government officials, "So when they read our intelligence, they will understand what we mean by it and the limits of what we say," and he believes some of that responsibility indeed falls on them.

A government source speaking on background said they stand by Telford’s testimony.

Trudeau also questioned the reliability of U.S. intelligence when he testified before the inquiry.

He stated that he does not always trust the intelligence information shared with him by the CIA, including a report suggesting that China may have interfered in the Liberal Party's nomination race.

The inquiry into foreign interference was prompted by a series of media reports citing unnamed sources and leaked documents, in addition to repeated calls from the opposition.

One of those media reports claimed that in 2019, senior national security officials informed officials in the Prime Minister's Office that then-liberal candidate Han Dong "was part of a Chinese foreign interference network" and that the party should "cancel Dong's nomination."

Allegations from 2019 included international students being bused to the Don Valley North federal riding, Dong's riding, to vote in the Liberal nomination contest.

Trudeau told the inquiry committee on April 10, "I did not feel there was enough information or reliable enough to justify this very significant step of removing a candidate."

"What perhaps concerned me most was that the service did not understand as deeply as political representatives do the spread of different community organizations being bused during nomination campaigns."

In what was widely interpreted as a rebuttal to Trudeau's comments, Vigneault used the final moments of the inquiry to defend CSIS's work.

He said he met with Trudeau in the weeks following that exchange and confirmed that he and the Prime Minister have a good relationship.

He added, "I listened carefully to what the Prime Minister said, and I believe his words were accurate. I think it's appropriate to consider nuances because this is an incredibly complex situation," stating that others in the intelligence community might not feel the same way.

He added, "Everyone has the right to their opinion."

The initial report from the public inquiry, issued earlier this month, stated that attempts by other countries to interfere in recent elections in Canada left a "stain" on the electoral system in this country, but ultimately did not affect which political party would form the government.

Shortly after the release of Commissioner Marie-Josée Houle's report, the federal government introduced a bill aimed at curtailing foreign interference in Canadian politics.

Bill C-70 would create new offenses for foreign interference, change how the Canadian Security Intelligence Service (CSIS) applies for arrest warrants, update rules about who can access sensitive intelligence information from CSIS, and finally launch a long-awaited foreign influence transparency registry.

Some of the changes reflect advice that Vigneault has provided for years about updating the Canadian Security Intelligence Service Act.

He said, "Since the passage of the CSIS Act in 1984, technology has completely changed—personal computers, personal phones, artificial intelligence—none of that existed."

When asked whether the length of time it took to introduce the bill made Canadian intelligence less effective, Vigneault stated that CSIS's work has become more challenging in recent years.

He noted, "Our ability at CSIS to obtain the information we need to produce intelligence so that we can protect Canadians has of course been challenged."

"That's why I believe the specific changes in Bill 70 will have an impact, but I have to be candid here and say that this will not be sufficient. Ultimately, more effort will be needed."

The bill already has its critics.

The Canadian Civil Liberties Association stated that Bill C-70 requires significant amendments to comply with the Charter.

Anaïs Bussiere McNicoll, the interim director of CCLA’s Privacy, Technology and Surveillance program, explained, "The proposed amendments to the Canadian Security Intelligence Service Act would significantly expand CSIS's ability to gather, analyze, and disclose sensitive information to third parties."

"This proposed expansion of the service's powers should be subject to stricter limitations to protect privacy rights."

Vigneault said he believes there is a balance to be struck.

"I don't think we can have a zero-sum equation where it is either national security or civil liberties. I believe Canadians are sophisticated, and that we can have the right discussion, and we can find the right way to empower the people who have sworn to protect Canadians to have the proper tools to do that."

"At the same time, do it in a way that respects our identity as Canadians, respects the Charter of Rights, and respects privacy rights."