I seem to recall the then-Prime Minister of Canada saying, to loud applause in the Canadian Parliament, "Canada Will Not Participate!"
I also recall that it was the position of the Canadian Government then that the matter of Iraq should be handled by the United Nations.
I don't see, then, why the Canadians are so upset.
Surely, they could simply get the justice they so fervently demand by referring their grievance against Iran to the United Nations.