But the notion that the U.S. should not attack another country unless that country has attacked or directly threatens our national security is not really extraordinary. Quite the contrary, that is how virtually every country in the world conducts itself, and it is a founding principle of our country . Starting wars against countries that have not attacked you, and especially against those who cannot attack you, is abnormal. ~Glenn Greenwald 
Yglesias  cites this as an example of how Greenwald is politically on his “left” and rather too far to the left for his taste. This is certainly one of those places where the right/left schema makes no sense at all to me, since I am light years to the right of Yglesias on everything else and yet I believe I am entirely in agreement with Greenwald’s statement here. This is not because I am discovering my inner left-winger, but because Greenwald’s statement is entirely consistent with any sane Christian and conservative attitude towards war. There is nothing particularly “far left” about repudiating and deploring wars of aggression, which seem to me to be the kind of war that Greenwald is rejecting. He might go beyond this and say that American forces should never be involved in wars of collective security or sent on peacekeeping missions (that would generally be my view), but that is not clearly implied here. Greenwald is saying that wanton aggression is not the norm, and wars of self-defense and national security are. He does not say whether collective security or peacekeeping is desirable (my wild guess is that he probably thinks that they are), though he does imply that it is fairly unusual. He says simply that the default condition for the use of force for most states is self-defense, which seems pretty clearly true.