well it all depends on the definition one has of war.
for Muslims, war is to kill their enemies. who are the enemies? all the non-muslims, especially Jews and Westerners (and if it is an American who’s killed, the delight is even greater). they don’t care about quality (civilian or military) but about quantity.
they killed civilians, yes but they were on the bad side, so target reached. and as they killed so many, they are considered as heroes for all those having the same definition of war as they had.
the hijackers are now models for all Muslims involved in their holly war (= which I define as terrorism), and it's the reason why terrorist attacks must be feared at any time.
(and I think that kind of meetings are a way to get organized)