Sanctions, boycotts and blockades oh my

You'd think that we're setting up for world war three. Sanctions never work because people cheat. This becomes the golden opportunity to for greater profits by squeezing the country sanctioned and no matter what they say it's always the people that get hurt and not those in power. We think that some how we can force nations to bow to our way of thinking. It didn't work with Japan in the 1930s and it hasn't worked with Cuba even today. Boycotts only work on a small scale. You might pressure a personality from the airwaves or a small business from a town but little effect in the overall scheme of things. People want to boycott BP but I'll tell you right now it won't work. They're too big. You may be successful in running them out of this country but, they'll just sell their oil to some other country at the highest price because that is what business does.
Then there's blockades. They never seem to work either. The only time I can recall one working was in the middle ages when after a year the city under siege was bombarded with bubonic plague corpses launched with catapults over high city walls causing a surrender. The first use of germ warfare.
The Cuban missile crisis started with a blockade but was short lived when Russia agreed to remove nukes from the island nation. That wasn't until the U.S agreed to remove its' nukes from Turkey, a little fact that got lost in history.
To sanction Iran is laughable because everybody isn't on board. Russia, China, and Brazil are still trading partners and even if they weren't we know that companies cheat. And speaking of being on board the fishermen of the Gulf need to round up what little cash is left from BP as investors are jumping ship as fast as a rig blow out.