They actually did take out multiple cities. There was a shot just before the explosion in NY where they panned across a number of black and white tv monitors showing a number of cities across the globe with similar explosions occurring.
Also, I'm not sure this spoiler tag thing works properly in Firefox. I thought the text was supposed to be invisible until we choose to view it, but all the spoilers are fully visible to me -- they just have a half-centimeter thick black border.
