A corollary question.
Could the hits against the World Trade Center be considered as air strikes, and on a parallel with US air and drone strikes where there are many civilians killed? I believe there were FBI and Secret Service offices in the buildings.
The US, after all, has caused considerable civilian casualties. Is there a difference because of the scale? Is that the only difference?
Both are terrorism, there's no definition which will exclude that, and both have enemies in the sight.
Or can we eliminate anything the US does as terrorism, and justified by our noble motives?