These military attacks were undertaken without submitting them to the formal American processes of war-making. Sovereign territory was invaded without regard to consideration of the nations involved. The rules have fallen one by one. Civilian women are the explicit targets of rape and sexual molestation, with the clear intent of destruction of cultures and their will to fight on. Captured soldiers are subject to mass execution and burial in unmarked graves, lost forever to families and societies.
Terrorism is merely the downward linear extension of such conduct.
It is indeed a degradation as relations among human beings deteriorate in an inexorable regression toward the primitive. It is not merely a political act, but a real political instrument, a continuation of political intercourse, a conduct of political intercourse by other means. The use of terrorism is, in this line of thinking, a further falling back to even rawer instincts. The first three are related to the perception of threat. Despite arguments that the Earth can handle even larger populations, this is not apparent to most humans who find their available space diminishing.