I don't often [ab]use my position as the publisher of content on www.quaker.org. Today, I feel led to do so.
The people who did this have committed a crime, not an act of war. Friends should encourage people to think of it this way. There is not a state in the world which will own up to this group. No state will try to protect the group that did this, presuming we have sufficient evidence to convince the world of their guilt. So, once there has been a capture, and a trial, justice will have been served.
It should be simple to position this act as a crime, not a war. When someone says "This means war!!! We must have REVENGE", just ask them "Against who?" Point out that individuals were behind this heinous act, and that individuals can be brought to justice.
Timothy McVeigh bombed the Alfred P Murrah Office Building. He was accused, tried, found guilty, sentenced, and a form of justice was attained. No war against his home state was contemplated.
Friends are anti-war, to be sure, but we are not now and have never been against justice. Indeed, war is its own form of injustice.
And then, once there has been closure, we must reconsider our role as world policeman. We need to understand why people hate us so much that they are willing to give their lives to hurt us. Do we act in ways that would offend us if other countries were doing them to us? Is our foreign policy one which we would never allow one US state to hold against another US state? Are we operating under the rule of law? Are we carrying out the instructions of a court? Are we taking sides in conflicts that don't involve us? Or are we acting as judge, jury, and executioner?