The federal government is forbidding the construction of new embassies on Ottawa's Sussex Drive following a stark RCMP assessment of the potential for "violent events" in the high-profile neighbourhood.
Countries with diplomatic missions already located on the well-known boulevard include the United States, France, Kuwait, Saudi Arabia and South Africa.
It is also home to Rideau Hall, where the Governor General lives, as well as the prime minister's residence at 24 Sussex. Justin Trudeau and his family are living in a house on the Rideau Hall grounds while federal officials consider badly needed renovations to the traditional address of Canada's leader.
Foreign Affairs Minister Stephane Dion was advised of the ban on new embassies in January by Daniel Jean, then his deputy minister, records released under the Access to Information Act show. Jean has since been named national security adviser to the prime minister.
"A recently concluded RCMP security assessment advises against any additional foreign embassies being located along Sussex Drive," says Jean's memo to Dion, obtained by The Canadian Press.
"As a result, the department will no longer be approving requests by diplomatic missions to acquire land in the affected zone."
Canada requires foreign states to obtain its consent before buying property for use as diplomatic chancery offices or official residences.
In summer 2015 the RCMP began a detailed assessment, at the request of Global Affairs Canada, of how construction of new embassies on vacant lots along Sussex Drive would affect the security of nearby Canadian and foreign facilities.
The Mounties looked at "risks associated with violent events likely affecting Canadian and foreign interests," but not scenarios involving espionage or protection of critical infrastructure, such as power grids and water systems, says a letter to Global Affairs from RCMP Chief Supt. Rosemary Abbruzzese.
"In summary, and after considering a number of factors, the RCMP concludes and recommends that the only appropriate risk response is risk avoidance by not allowing any additional foreign missions to be located on Sussex Drive."
Global Affairs is aware of only a few available properties that fall within the affected zone, said department spokesman Michael O'Shaugnessy.
Among them is 50 Sussex Drive, formerly known as the Canada and the World Pavilion – a stylish building overlooking the Ottawa River that intended to highlight the international achievements of Canadians.
An embassy on the cliff that slopes down to the scenic river is difficult to secure, said Chris Mathers, a former RCMP officer who now works as a crime and risk consultant.
"It's pretty steep but it's not so steep that you couldn't climb up," he said in an interview.
The Mounties might also be concerned that a large truck bomb would damage more than one embassy, and therefore spreading out the missions in the national capital increases security.
"I think it's the right move. We don't need to cluster them all in one place," Mathers said.
"If something bad happens, it's only going to happen in one area and it won't expose the entire diplomatic community to danger."