The organisation that supports US troops who refuse to fight, COURAGE TO RESIST, has an excellent article giving many of the reasons against the war in Afghanistan, see: http://www.couragetoresist.org/x/content/view/738/1/
Joe Glenton
It is encouraging to see mention of Joe Glenton as one of the first UK war resistors, see towards the end of: http://www.couragetoresist.org/x/content/view/741
