Left - at least the moderate left in italy, I don't know what kind of American left you're talking about - is anti war in an anti _offensive_ war sense, not against a defensive war or against defending another more or less allied country from being invaded by another country
I am not sure of course, but I guess the same would be true of other similar center left parties in europe
I am not sure of course, but I guess the same would be true of other similar center left parties in europe