Canada prefers the Two Amigos to the Three Amigos when negotiating with its most important neighbour, the United States - fearing that adding NAFTA partner Mexico to talks erodes the benefits for Canadians.
It's a concern Canadian politicians are too polite to voice publicly but one that WikiLeaks aired for all to see Wednesday in a U.S. diplomatic cable.
While Mexico is a partner of Canada and the United States in the groundbreaking North American Free Trade Agreement, the three-way relationship has weakened in recent years - a period in which Ottawa slapped entry restrictions on Mexicans, to the anger of that country's government.
A 2009 briefing for U.S. President Barack Obama before the "Three Amigos" talks in Guadalajara, Mexico, with Stephen Harper and Mexican President Felipe Calderon cautioned the U.S. leader about Canadian discomfort with discussions that include Mexico, a cable released by WikiLeaks shows.
"Canada remains at times concerned that trilateralism comes at the expense of its bilateral relationship with the United States," the U.S. embassy in Mexico wrote.
The U.S. diplomat writing the memo hastened to add that Canada has assured the Americans "it does value" summits between North American leaders.
Recent perimeter security border talks launched between Canada and the U.S. are a perfect illustration of Ottawa's wish to keep Mexico out of high-priority negotiations. Ottawa and Washington, without Mexico City, embarked on bilateral discussions in January that would deepen relations to protect the continent from terrorism but ease two-way trade.
It's a dramatic shift from the previous three-way approach to the matter: the Security and Prosperity Partnership that was launched in 2005 between all NAFTA partners but later abandoned.
In a cabinet document obtained by The Globe and Mail last December, the Harper government was warned to expect a backlash from Mexico over the new border talks. Officials cautioned that Mexico "may raise concerns about not being included in the vision."
Colin Robertson, a former Canadian diplomat, said Canada is frustrated when Mexico is included in meetings with the Americans because its drug war and border troubles tend to dominate discussion - relegating Ottawa's priorities to the back seat.
"The Mexican issues, when Mexico is in the room, become transcendent because in grand strategy terms they are more important: drugs, smuggling, guns and mayhem - the idea of an incipient failed state," Mr. Robertson said.
"You end up with basically two bilateral discussions [with the U.S.] but ours becomes much shorter."
He said Mexico commands significant attention in the American mind in part because of mass migration to the United States. "There are now more Americans of Latino descent in America then there are Canadians, period," he said.
Mr. Robertson, however, feels it's a strategic mistake for Canada to leave Mexico out of discussions with the Americans about greater continental co-operation.
The Canadian government refuses to discuss the latest U.S. memo dredged up by WikiLeaks.
"This is not a Canadian document. We don't comment on leaked documents," said Lynn Meahan, press secretary for Foreign Affairs Minister Lawrence Cannon.
The Mexican embassy in Canada did not respond to a request for comment.