I think the bigger question is to question what terrorism is.
Usually, 'terrorism' is asymmetrical, guerrilla warfare against a stronger, well-organized force. Many people have had to use such tactics against a better army...Even America did in the war for independence. We did a lot of things to the British regulars that were either unconventional or illegal in warfare at that time.
Now, the bigger heart of the issue would be if blowing up civilian targets is justified in an asymmetrical war. I'd argue that only in a few, rare cases has it been justified - I would cite nuclear warfare against Japan in WW2 as one of the rare viable times its justified. However, I'd say that it is very rare that attacking civilian targets is justified.
Back from the dead, I'm afraid.
