WASHINGTON  In early 2008, American diplomats stationed in Ottawa turned on their television sets and were aghast: there was an “onslaught” of Canadian shows depicting “nefarious American officials carrying out equally nefarious deeds in Canada,” from planning to bomb Quebec to stealing Canadian water supplies.

In a confidential diplomatic cable sent back to the State Department, the American Embassy warned of increasing mistrust of the United States by its northern neighbor, with which it shares some $500 billion in annual trade, the world’s longest unsecured border and a joint military mission in Afghanistan.

“The degree of comfort with which Canadian broadcast entities, including those financed by Canadian tax dollars, twist current events to feed longstanding negative images of the U.S.  and the extent to which the Canadian public seems willing to indulge in the feast  is noteworthy as an indication of the kind of insidious negative popular stereotyping we are increasingly up against in Canada,” the cable said.

A trove of diplomatic cables, obtained by WikiLeaks and made available to a number of publications, disclose a perception by American diplomats that Canadians “always carry a chip on their shoulder” in part because of a feeling that their country “is condemned to always play ‘Robin’ to the U.S. ‘Batman.’ ”