The ally needs some motivation to take on someone else's existential threats as their own. Lots of treaties and posturing may dampen would-be aggressors' motiva

The ally needs some motivation to take on someone else's existential threats as their own. Lots of treaties and posturing may dampen would-be aggressors' motivation, but as the USA has demonstrated of late re: Ukraine vs Russia, all too often promises of military protection don't mean $#!^.