Modern armor and weaponry can be quite advanced, but their strength comes from the fact that they're combined with large armies that need mass produced and interchangeable components. Insurgencies and asymmetric warfare can be waged by small cells and individuals using unconventional methods.
That is to say, yes, Israel and the US and Russia can get to a single cell by obliterating the entire neighborhood or town, but that creates even more enemies to deal with. Small scale surgical attacks and unconventional sabotage can and do bring them to a halt without collateral damage which is key
Empires fail because they stop considering people as important. They get sloppy and end up creating the force that overthrows them through their disregard of life. When you start talking about "acceptable casualties" you've already lost the mental war. You're seeing people are abstract numbers.
The key to winning a conflict against empire and the key to not becoming yet another empire is cultivating a core trait of empathy that respects life above all else and rejects violence as anything but a tool for self defense and liberation. It doesn't teach it only harms. We need radical compassion