Those have been part of the common language of city defense since at least Operation: Desert Storm in 1991, and in regular use for as long as sieges (and theref

Those have been part of the common language of city defense since at least Operation: Desert Storm in 1991, and in regular use for as long as sieges (and therefore cities) have been a thing. One of the ways to win a war without winning a battle is to make winning so morally costly to your enemy that their own troops balk at the doing. Its not a super effective method, and usually fails (propaganda tends to win in that particular game of rock-paper-scissors), but it can certainly be effective as a delaying tactic, or as a method to damage your enemy's morale. There have always been statespeople and military leaders who argue that human shields are unsporting, but the main pressures on military strategy are evolutionary, rather than ethical. Thus, if its horrific but it works, it must not be that horrific. More broadly, arms races typically amount to "we believe the other side has the technology to commit X atrocity. We therefore need the same ability to commit that atrocity, else we appear weak"