In the end most of us want peace
It is indeed a vicious circle. No one can guess for how long intelligent people have been saying: Violence begets violence. But it is also very much a catch 22. If the USA had not responded to Saddam and Iraq. Ten years down the road all of the people that were protesting against the invasion would have been saying :"Why didn't you save them? You the big and "powerful" USA."
The USA is one of the few countries that could finance the upsurp of a psychotic, egomanical, murderous dictator. Canada surely couldn't. We are just now digging ourselves out of our own debts and rebuilding a decimated military, brought on by continuous financial cuts by past governments. Other countries couldn't as well. Some due to their simple geographical closeness to the problem which would put them in a precarious position, exposing their general population to much more of a risk of being utterly devestated by any war.
The problem the USA faces now is, how do we get out of this? More and more people in the USA are becoming disillusioned with it all. Families and friends just want their soldiers home now. But if the USA leaves too quickly, and another fatalist regime takes control, the USA will be blamed for that as well. Then all of the same anti-Iraq war people would be saying, "It's your morale responsibility to take care of them."
So where, pray tell, is the line to be drawn?