The RCMP conducted at least two prior investigations into leaks of sensitive information involving naval projects before this week's suspension of the military's second-highest ranking officer, sources tell CBC News.

The revelation comes at the same time the Trudeau government has quietly moved to reassure allies that no foreign intelligence data was compromised in relation to the controversy involving Vice-Admiral Mark Norman.

A series of federal, defence and industry sources say the RCMP conducted inquiries about how the media got hold of a decision, in late 2015, that temporarily halted plans to lease a new military supply ship. The story was reported, at the time, by CBC News and The Canadian Press.

Inquiries were also made about a leak in the fall of 2014 about a decision, by the former Conservative government, to sole-source the $800-million purchase of new Sea Sparrow missiles for the frigates. That story was reported by Postmedia.

The dates, timing and conclusions of those investigations remain shrouded in mystery, but they have not, as of yet, resulted in any charges.

Leaks predate political storm

But the fact the investigations took place at all indicates that scrutiny of naval acquisitions predates this week's political storm over the suspension of the military's No. 2 commander.

The RCMP were asked for comment late Thursday, but no one was immediately available.

Sources who spoke to CBC News on the condition of anonymity, because of sensitivity of the file, were unable to say how — if at all — the investigations connect with the case involving Norman. He was relieved of his duties, but not stripped of his command, as vice-chief of defence staff on Monday.

The French navy frigate Aquitaine is pictured at berth in Halifax in 2013. The Paris-based DCNS wants Canada to consider the frigates for the Canadian Surface Combatant program. (Andrew Vaughan/Canadian Press)

And while the Liberal government and National Defence have maintained a wall of silence, a series of leaks to multiple media organizations indicate the Mounties are examining allegations that Norman somehow divulged classified data, perhaps to the shipbuilding industry.

The alleged disclosures that seem to have caught the RCMP's attention are recent and possibly related to the newly launched competition to design the navy's new frigates, a high-stakes multibillion-dollar, multi-year program.

RCMP skeptical in past probes

The RCMP have sometimes as a matter of routine opened national security probes into defence-related stories leaked to the media.

Notably, they conducted a six-month probe in 2010 into a Globe and Mail story about the F-35 fighter, but internal documents released to The Canadian Press in 2012 show investigators were skeptical that information in the story jeopardized "the safety of Canada" or that it "shed new light on secrets."

In light of the assurance given to allies that "Five Eyes" intelligence data is safe, the question of what may have been disclosed is taking on new relevance.

The fact the RCMP did not make an immediate arrest is significant, said Errol Mendes, a law professor at the University of Ottawa who worked in the Privy Council Office in Paul Martin's government.

"It suggests we are dealing with the leaking of domestic procurement information," he said. "People at that level have top security clearance, and when they're cleared at that level, they sign saying they won't release anything for the rest of their life. It's very strict."

National security vs. political secrets

But other experts say drawing the line between a national security secret and a political secret was blurred under the Conservatives.

Under Stephen Harper's government, the definition of what could be considered secret cabinet information was expanded through rewritten federal treasury board regulations in 2013.

Departmental lawyers were given wider discretion to decide what constitutes a cabinet secret — known as a "confidence."

The result has been that data — previously considered innocuous — was labelled a state secret and hidden not only from the public, but from members of Parliament, parliamentary watchdogs and even the information commissioner.

"It extends coverage of the cabinet confidences and has created more secrets," said Michel Drapeau, a retired colonel and military law expert.

In opposition, the current Liberal government complained about how often the Conservatives declared matters to be cabinet secrets, but have not moved to reverse the changes.