A top secret document retrieved by American whistleblower Edward Snowden reveals Canada has set up covert spying posts around the world and conducted espionage against trading partners at the request of the U.S. National Security Agency.

The leaked NSA document being reported exclusively by CBC News reveals Canada is involved with the huge American intelligence agency in clandestine surveillance activities in “approximately 20 high-priority countries."

Much of the document contains hyper-sensitive operational details which CBC News has chosen not to make public.

Sections of the document with the highest classification make it clear in some instances why American spymasters are particularly keen about enlisting their Canadian counterparts, the Communications Security Establishment Canada.

"CSEC shares with the NSA their unique geographic access to areas unavailable to the U.S," the document says.

The briefing paper describes a "close co-operative relationship" between the NSA and its Canadian counterpart, the Communications Security Establishment Canada, or CSEC — a relationship "both sides would like to see expanded and strengthened.

"The intelligence exchange with CSEC covers worldwide national and transnational targets."

CSEC offers resources for advanced collection, processing and analysis, and has opened covert sites at the request of NSA - NSA memo retrieved by Edward Snowden

The four-page missive is stamped “Top Secret” and dated April 3, 2013. That makes it one of the freshest documents Snowden was able to walk away with before he went public in June.

The briefing notes make it clear that Canada plays a very robust role in intelligence-gathering around the world in a way that has won respect from its American equivalents.

Wesley Wark, a Canadian security and intelligence expert at the University of Ottawa, says the document makes it clear Canada can take advantage of its relatively benign image internationally to covertly amass a vast amount of information abroad.

"I think we still trade on a degree of an international brand as an innocent partner in the international sphere," Wark said. "There's not that much known about Canadian intelligence.

"In that sense, Canadian operations might escape at least the same degree of notice and surveillance that the operations of the U.S. or Britain in foreign states would be bound to attract."

The intimate Canada-U.S. electronic intelligence relationship dates back more than 60 years. Most recently, another Snowden document reported by CBC News showed the two agencies co-operated to allow the NSA to spy on the G20 summit of international leaders in Toronto in 2010.

But what the latest secret document reveals for the first time is just how expansive Canada's international espionage activities have become.

CSEC set up 'covert sites at the request of NSA'

The NSA document depicts CSEC as a sophisticated, capable and highly respected intelligence partner involved in all manner of joint spying missions, including setting up listening posts at the request of the Americans.

"CSEC offers resources for advanced collection, processing and analysis, and has opened covert sites at the request of NSA," the document states.

Edward Snowden, a former NSA contractor, has leaked top-secret documents into the U.S. spy agency's activities over the past few months. (The Guardian/Associated Press)

Thomas Drake, a former NSA executive turned whistleblower, says it's no surprise Canada would accede to the U.S. agency's requests: "That's been the case for years.

"Just think of certain foreign agreements or relationships that Canada actually enjoys that the United States doesn't, and under the cover of those relationships, guess what you can conduct? These kinds of secret surveillance or collection efforts."

Drake says he worked with CSEC on various projects while he was at the NSA, and the Canadians were "extraordinarily capable."

CSEC conducts much of its foreign cyber-spying operations from its headquarters in Ottawa, using some of the most powerful computing equipment in the country to intercept foreign phone calls and monitor internet communications in nations around the globe.

Its American counterpart does the same, but is itself currently the target of a widespread internal probe by the U.S. administration in the wake of leaked documents from Snowden showing the NSA has been collecting masses of information on millions of ordinary Americans.

Wark reviewed the leaked document at the invitation of CBC News, and says he isn't surprised CSEC would be asked by the NSA to set up covert foreign spying operations.

He says it is not uncommon for embassies and consulates to be used as listening posts when a close proximity to targets is required.

But he also points out it all comes with significant risks to Canada — namely, getting caught "can create huge diplomatic fallout."

High-level approval required

Aside from compromising the actual intelligence operation, Wark says, an exposed spy mission can imperil Canada's other diplomatic operations — "the political contacts, the trade contacts, the generation of goodwill between the countries and any sense of co-operation."

Wark says if a country feels targeted by a Canadian embassy, it can put everyone working there under a cloud of suspicion: “Are they really diplomats or are they spies?”

As a result of those risks, Wark says, approval for CSEC to establish a covert spying post at the request of the NSA would have to come from the ministerial level of the Canadian government — or even from the prime minister himself.

"It's far too politically and diplomatically sensitive, and the consequences of being discovered are far too great, for it to be simply an operational matter for an intelligence agency," he says.

"In the past, it certainly has been and it should be today, a matter of very senior political sign-off."

Canada and the U.S. have long shared security intelligence with sister agencies in the U.K., Australia and New Zealand – the so-called "Five Eyes" partnership.

But the latest secret Snowden missive shows CSEC and the NSA becoming physically intertwined.

"Co-operative efforts include the exchange of liaison officers and integrees," the document reveals, a reference to CSEC operatives working inside the NSA, and vice-versa.

It notes the NSA also supplies much of the computer hardware and software CSEC uses for encryption, decoding and other state-of-the-art essentials of electronic spying needed for "collection, processing and analytic efforts."

In return, the NSA acknowledges that its Canadian counterpart provides the partnership with its own "cryptographic products, cryptanalysis, technology and software."

Finally, the U.S. agency says CSEC has increased its investment in research and development projects "of mutual interest."

CSEC employs about 2,000 people, has an annual budget of roughly $450 million and will soon move into an architecturally spectacular new Ottawa headquarters costing Canadian taxpayers almost $1.2 billion.

By comparison, the NSA employs an estimated 40,000 people plus thousands of private contractors, and spends over $40 billion a year

NSA whistleblower Drake says the problem is that both CSEC and the NSA lack proper oversight, and without it, they have morphed into runaway surveillance.

"There is a clear and compelling danger to democracy in Canada by virtue of how far these secret surveillance operations have gone."

The office of Defence Minister Rob Nicholson, who is responsible for CSEC, issued a written statement saying CSEC’s activities are subject to review by an independent commissioner.

A spokesperson for the U.S. government said: "While we are not going to comment publicly on every specific alleged activity, we have made clear that the United States gathers foreign intelligence of the type gathered by all nations."