The CBC News report earlier this week that Canada hacked into Mexican computer networks to gather intelligence is expected to worsen an already tense relationship with a key trading partner.

"This type of cyberwarfare and cyberspying is generally done to countries that are considered your enemy, not your friends, certainly not your partners in a free trade agreement," said Andres Rozental, a former Mexican deputy foreign minister and career diplomat.

Mexico’s ambassador to Canada refused to comment on the story that Canada’s electronic spy agency, along with its U.S. counterpart, hacked into computer networks in Mexico.

"I can confirm that we are presently in contact with Canadian authorities regarding this issue and do not have further comments to make at this time," embassy spokesman Raul Saavedra said in a written statement on Wednesday.

CBC News reported on Monday that the U.S. National Security Agency and Canada’s Communications Security Establishment "co-operate closely" on computer network access and exploitation in hotspots like North Africa and the Middle East, but also in friendly nations like Mexico and in Europe.

Those details came out of a 2013 memo, written by the NSA, that was among a cache of documents obtained by U.S. whistleblower Edward Snowden, and analyzed jointly by CBC News and the U.S. news site The Intercept.

The memo didn’t name the spy agencies' specific targets in the countries, nor did it detail the tactics used.

On Wednesday, Julian Fantino, the associate minister of national defence, refused to comment on details, but said that CSE operates within well-established and supervised parameters of the law.

"Moreover, all of our efforts are consistent with our mandate to protect Canadians from terrorist threats and cyberattacks."

Asked about CSE's surveillance practices toward friendly nations at the parliamentary committee reviewing her recent appointment as the new head of the secretive agency, Greta Bossenmaier would say only: "We conduct our foreign intelligence activities according to our government's intelligence priorities."

To that, NDP MP Elaine Michaud retorted that the inability to get answers to such legitimate questions further illustrates why it's important for Canada to have parliamentary oversight of the agency's actions.

Why spy on Mexico?

This marks the first time that Canada has been accused of systematically spying on such a close trading partner. Though, in 2013, the federal government faced accusations of surveilling the communications of Brazil’s mining and energy ministry.

Leaked Snowden documents revealed that the NSA and its Canadian counterpart, CSE, is conducting computer network access and exploitation in Mexico, Europe, North Africa and the Middle East. (Evan Mitsui/CBC)

Previously leaked NSA documents, however, have tied the American agency to spying on Mexican officials. The agency hacked into the Mexican president’s email account in 2010 and, two years later, snooped on the communications of a presidential candidate — currently President Enrique Peña Nieto — according to the documents.

Given how closely the U.S and Canadian agencies work together as part of the Five Eyes spying partnership, a grouping that also includes the U.K., Australia and New Zealand, experts suggest high-level public officials may have been among the Mexican targets.

Certain Mexican officials have been targeted in the past. In 1995, a CSE intelligence analyst revealed she had monitored communications from the Mexican embassy during NAFTA negotiations in 1992-3, according to newspaper reports at the time.

Rozental, a board director at the Waterloo-based think tank Centre for International Governance Innovation, notes the CSE may also have been gathering economic intelligence because Canada has an enormous number of companies operating in Mexico, including in the mining, aerospace and auto industries.

Carlo Dade, who studies Mexican-Canadian trade relations, doubts the targets involved spying for businesses, saying it would be too difficult for the spy agency to figure out which of so many companies to favour with the intelligence.

“If we were to gain intelligence about the automobile sector, who would we pass that along to? Ford, Chrysler, GM? Do we have to share with Nissan, too, because they have plants in Canada?" asked Dade, the director the Centre for Trade and Investment Policy at the Canada West Foundation.

It’s far more likely, he says, that CSE analysts were tapping into networks due to security issues, such as an alleged assassination plot of a Saudi diplomat on U.S. soil in 2011, which had Mexican connections.

Ensuring the safety of the 1.5 million Canadian tourists flocking to Mexican beach resorts may also motivate the spying, Dade suggested.

Rocky relationship

Canada’s 70-year relationship with Mexico has been rockier of late, particularly since the federal government introduced strict visa requirements for Mexican travellers in 2009, to reduce asylum claims.

Relations between Prime Minister Stephen Harper and Mexico's President Enrique Pena Nieto remain tense. (Eduardo Verdugo/The Associated Press)

The rules were eased a bit in 2014, but the Mexican government has asked Canada for years to completely remove the visa requirement, and the issue has become a sticking point in relations between the two countries.

President Peña Nieto cancelled a trip to Canada in 2014 to show his displeasure with the Harper government over the visa policy.

Also, the annual Three Amigos summit scheduled to take place in Canada this year has been indefinitely postponed.

News that Canada and the U.S. were jointly spying on Mexican targets will inevitably add to current tensions.

"It never looks good when you’re spying on your friends, even when everyone else does it and even if everyone knows that everyone does it. It still doesn’t look good and people are going to be upset," said Dade.

Despite that, Dade expects the Mexican government will remain largely quiet on the spying issue, the opposite approach than Brazil.

Brazilian President Dilma Rousseff said she'd be demanding an explanation from Canada, while the foreign affairs minister took the serious diplomatic measure of summoning Canada's ambassador to the country to explain the allegations.

Mexico, says Dade, is "integrated with us in a way that Brazil simply isn't, so it's a long-term relationship and we're going to have to work it out."