Huh?
When was the US attacked? Last time was WWII. If the US is attacked, it should fight back, win the war and then come home, not engage in endless foreign adventurism...it drains the resources of the US, leads to worldwide resentment and is simply unnecessary.
9/11/01
Oh, sorry... does it only count if the attack is made is made by a sovereign country using tanks or bombs or warships or fighter aircraft? This is the 21st century and the face of war has changed forever.
Idiotic "inside job" conspiracy theories aside, are you really going to sit there and tell me that wasn't an attack on the US, on US soil? Not to mention the failed attempt to bring down the WTC in 1993.
WWII was considered unnecessary and unjust by many groups... until certain things happened, like Germany invading Russia or the attack on Pearl Harbor. Then even groups like the Isolationists, Socialists, Nationalists, Pacifists, et al signed on. What would need to happen before you would consider US involvement to be justified?