[cgbg]

The problem with sanctions is not that they do not work—it is that they are a form of warfare.

If you start sanctioning too many countries (especially powerful ones) they may decide to band together and declare war on you.

Example: The sanctions on Japan are generally agreed to be one of the key factors that caused them to attack Pearl Harbor.

[DannyTN]

+1 It's true if you over do it, you can lose effectiveness. But mostly they work.