Comment by potato3732842

On a national scale sanctions aren't there to stop a country from doing things or forcing regime change. They're there to cost enough money to circumvent that it robs them of growth over time to make them into a non-threatening poor backwater over a decades long period.

This is basically what the US did to most of its "makes actual stuff" economy over the past 50yr.

When it comes to banking laws and the like it's not about being watertight. It's about holding enough water that what leaks out is small enough you can crush it with the state jackboot without enough collateral damage to really piss people off and that the cost of circumvention is high enough that you can't make "real money" outside the law at scale.