Samuel Adams
Although I myself am not American, if called I shall offer my life for liberty. Anyone know if it is possible to enlist in the U.S. military on a Visa?
My granfather (born in Greece) earned his American citizenship by serving in the U.S. Army. He earned it the hard way. He saw combat in WWI, and received a Purple Heart.
Also, the Canadians listed on the Vietnam Memorial total in excess of 1000 I am told.
If you are serious, call a recruiting station near where you live (what -- 75% of Canada's population is within a hour's drive of the US border), and tell them what you want to do. They can answer all of your questions for you. I suspect they will tell you to drive across the border, and sign up.