OTTAWA - The Conservative government maintained a stony silence Wednesday in the face of serious questions about how a navy intelligence officer was able to sell Canadian military secrets to Russia for four years.

Critics and intelligence experts alike called on the government to explain how Sub-Lt. Jeffrey Delisle managed to maintain a top secret security clearance that allowed him to smuggle a treasure trove of data out of military installations on a USB stick.

They also called for a full accounting of how the government planned to prevent future security breaches and what it was doing to reassure allies — including the United States and Britain — with whom they regularly share sensitive intelligence.

"We don't comment on matters of national security," said a spokeswoman for Public Safety Minister Vic Toews.

The office of Foreign Affairs Minister John Baird gave the same response.

"It's mind-boggling," said Wesley Wark, a University of Toronto intelligence expert, who served four years on the government's recently abolished federal panel of national security advisers. "Every level of the security system failed."

Wark said Delisle's security clearance, which the intelligence officer had held since 1998, would have been renewed every five years in an exhaustive background check that would have involved interviews with his friends and family as well as the disclosure of other personal information.

Since Delisle had been working for the Russians since 2007, Wark called on the government to specify when his last security check was done and whether he was subjected to a lie detector test.

"Something clearly went wrong in the clearance process," said Wark.

The government owes Canadians and its allies an explanation about how the breach was allowed to happen, and what can be done to prevent future breaches, said Jack Harris, the NDP defence critic.

"You can't walk out of a diamond mine with a pocketful of diamonds. How is it you can walk out of a top secret naval intelligence facility with a pocketful of secrets on a thumb drive?" Harris said.

"This happened over a period of four years on this government's watch and they don't seem to have been called upon to answer for it."

Delisle pleaded guilty Wednesday in a Halifax courtroom, pulling back the veil on the double life he led since he walked into the Russian embassy in 2007 and offered his services. He was arrested in January after a trip last fall to Brazil, where he met his Russian handlers, aroused suspicion upon his return to Canada.

Court was told Delisle worked at Trinity — the name for the military all-source intelligence "fusion" centre on the East Coast — which experts have said would provide tactical assessments primarily to Canadian warships and aircraft, both at home and overseas.

Court heard that Delisle would have had access to the facility's secure and unsecured systems that contained information from Canada and her allies, and that he shared mostly military data. It also included material about organized crime, political players and a contact list that was described as a "who's who of military personnel" with email addresses and phone numbers.

While still a reservist in the late 1990s Delisle declared bankruptcy, a fact that would have shown up in his background check prior to joining the regular forces in 2001 and when he later applied to become an officer, Wark said.

That should have raised red flags and made him the subject of further scrutiny by the security agencies who later hunted him, he said.

Wark said the way Delisle mined secrets and slipped the information out the door shows the Canadian government "has learned nothing from the Bradley Manning case," the U.S. Army soldier accused of passing hundreds of thousands of documents to the whistle-blowing Web site Wikileaks.

"Everything is proportional. When we do a damage assessment we have to stay rational about it and say, that really hurts but does it hurt as much as the Manning thing? Probably not," said Ray Boisvert, a retired assistant director of intelligence at CSIS, Canada's spy agency.

"My personal view from experience is, yes there are some tough conversations around the table with your allies when something like this happens. But all of them are very circumspect because all of them have had the same problem. They've all had moles. They've all had leaks."

Boisvert said Canada has no choice but to engage with Russia because it has common interests, especially in the Arctic. The same goes for China, which is routinely criticized for spying.

"They must engage those countries, but do so with eyes wide open," he said.

"Be aware that as you engage those countries through the front door they have no qualms about getting at you through the back door."

Also on HuffPost:

Declassfied CIA, FBI Spy Gear

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  • Suicide Pin

    If a CIA operative were caught, he could choose capture or death by this pin. When twisted the right way, the silver dollar would unleash a pin coated in saxitoxin. Its user would die in seconds from the poison.

  • Assassination Umbrella

    Spies aren't usually assassins. But some weapons, like this umbrella, have been used in the field. The assassination umbrella is equipped with a pellet of toxic ricin that will infect and kill its target slowly over the course of a few days. Its last known use was on Bulgarian defector and BBC reporter Georgi Markov in London, 1978.

  • Dead Drop Brick

    Spies in Moscow in the 60s had a variety of "dead drops" they could use to secretly pass around notes and other contraband, including these hollow bricks.

  • Dead Drop Rat

    Rats' hollowed-out bodies also served as an effective dead drop for money, notes and other contraband being moved around Moscow.

  • Exploding Coal Paint Set

    Spies would use fake, exploding coal to sabotage supply lines -- and this paint set to make the coal look real.

  • Matchbox Camera

    In the 40s, spies were using cameras smaller than your smartphone!

  • Sleeping Beauty

    Think you could be a spy? Try floating a one-man submarine into Singapore harbor and planting mines on Japanese ships in World War II. Not easy, but this submersible is cool.

  • Lock Picks Kit

    And they all fit in this handy dandy sheath.

  • Time-Delay Pencil Detonators

    With these bad boys, you could even get away BEFORE the explosion.

  • Beano Grenade

    The OSS designed the Beano grenade to feel like a baseball and explode on impact -- rather than bouncing away from its target and blowing up elsewhere.