An exchange of armed forces personnel between Canada and the USA. X number of troops from the USA come up to Canada for "Winter training" yearly, the same number of Cannucks go south and desert train. Each group is stationed, as if they're part of the home forces.
When the USA invaded Iraq, the Canadians there went with their home troop over the ocean and into Iraq. They were effectivly Americans at that point, but still Canucks. Our GVT didn't pull them back home or refuse them from going because 'we're allies' and even though we can't, as a political force clap and cheer what we feel was an early invasion, we sure as hell remember that the USA is our ALLY! So, we didn't pull the troops. Furthermore, we released the American troops stationed in Petawawa, Ontario...back into the USA, so they could go to war in Iraq.
That's why there were Canadians in Iraq...'we're allies!
Just don't expect us to jump every time the USA says "Squiggy"...cause we also happen to be a strong and independant nation.
Nuff said?