> Damaging property for political ends

Damaging military equipment is a military end, not a political one. If it were otherwise, then a military attacking a military would definitionally be terrorism. At that point, you've removed the utility of the word "terrorism" from English and made it synonymous with "armed conflict."

Terrorism being done chiefly to change policies by terrorizing people through symbolic acts is a constrained, generally-accepted definition of terrorism.

Contrast with 9/11, where symbols of American capitalism, filled with civilians, were attacked in order to terrify people who have nothing to do with those buildings into supporting changes in policy that hurt the US.