Canada's Prime Minister Stephen Harper (R-L), his wife Laureen, Prime Minister-designate Justin Trudeau and his wife Sophie Gregoire talk at a ceremony to commemorate the October 2014 attack on Parliament Hill, at the National War Memorial in Ottawa,

Canada's Prime Minister Stephen Harper (R-L), his wife Laureen, Prime Minister-designate Justin Trudeau and his wife Sophie Gregoire attend a ceremony to commemorate the October 2014 attack on Parliament Hill, at the National War Memorial in Ottawa, Canada

Canada's Governor General David Johnston (R-L), Prime Minister Stephen Harper, his wife Laureen, Prime Minister-designate Justin Trudeau and his wife Sophie Gregoire attend a ceremony to commemorate the October 2014 attack on Parliament Hill, at the National War Memorial in Ottawa,

Canada's Prime Minister-designate Justin Trudeau and his wife Sophie Gregoire arrive at a ceremony to commemorate the October 2014 attack on Parliament Hill, at the National War Memorial in Ottawa,