The just response to this terrible event should be to go immediately to the world community, the United Nations. The rule of international law should be marshaled, but it's probably too late because the United States has never done that; it's always gone it alone.
Speaking as a New Yorker, I found it (9/11 event] a shocking and terrifying event, particularly the scale of it. At bottom, it was an implacable desire to do harm to innocent people.
It [9/11 event] was aimed at symbols: the World Trade Center, the heart of American capitalism, and the Pentagon, the headquarters of the American military establishment. But it was not meant to be argued with. It wasn't part of any negotiation. No message was intended with it. It spoke for itself, which is unusual.
This [9/11 event] was bloody-minded destruction for no other reason than to do it. Note that there was no claim for these attacks. There were no demands. There were no statements. It was a silent piece of terror. This was part of nothing.