Some forget that Canada and others also had debate. Also sent soldiers to Afghanistan for what they considered a just cause. Then war as it always does, reared its ugly head.
No, NATO obligations is a red herring they all could have shirked treaty obligations.
"In July 2008, Canadian soldiers killed a five-year-old girl and her two-year-old brother after their vehicle got too close to a convoy. The father said afterwards that “if I get a chance, I will kill Canadians.” Due to an agreement between Kabul and Ottawa, Afghans had no legal right for compensation if they were hurt or their property damaged by Canadian soldiers...Later, the video shows a Canadian commander saying “too bad for you if you don’t want to tell us where the Taliban are hiding. We will come and kill them. We will drop many bombs and fire all over. Is this what you want? Well then continue telling us nothing.”."
If American can learn a lesson IMO it should be. Keep the troops in the barracks where they belong. Use diplomats to developed coalitions of sanctions and pressures on misbehaving countries.
Canada on the other hand has natural restraints on military adventurism. 1.9% of GDP defense spending means few bombs, troops and almost no drones.