Do Sanctions Make It Easier to Declare War?

Interesting theory--sanctions don't work, everyone realizes they don't work, but the sanctions make it easier to declare war against the target country:

http://www.balloon-juice.com/2010/06/09/sanctioning-iran/

Did sanctions work Iraq? Or did they just make it easier for the U.N. Security Council to grant permission to go to war?

Once you show that x country is violating a bunch of rules related to sanctions, you can then argue it is more likely that x country is violating another set of rules, like WMDs, nuclear weapons, etc.