>>The point is, trade is fungible.
>>If the US does not want to buy your sugar and cigars, then sell them somewhere else.
>>If you can't buy Chevrolets, check out the Toyotas or Volkswagens.

That theoretical argument could be applied to (say) an embargo of New Zealand by Australia. You're denied bread, so eat some cake! Yes NZ could substitute trade with others- but close large markets are better than distant ones for whom your business is a mere blip. In the case of Cuba, goods shipped via the US a mere 90 miles away, ought to be the most efficient and effective way to trade, whether it be Chevrolets or Toyotas. Whereas shipping Toyotas directly into Havana is an order of magnitude more difficult with the US threatening sanctions on surrounding nations if they help the transport ship on its way.

There's no question that the embargo wasn't intended to prevent just trade with the US, but to limit as much trade as possible. Did you see Al's reference to Canada making it illegal to cooperate with US extraterritorial pressure? Did you see Luis referring to punishments if South American nations dared to trade with Cuba? Sheesh, a cynic might argue that Cuba was pushed into the arms of the Ruskies and then was punished for it, for 50 years.

If I could refer back to one of those opening Wikipedia sentences:

After the Castro socialist government came to power on January 1, 1959, Castro made overtures to the United States, but was rebuffed by the Dwight D. Eisenhower administration, which by March began making plans to help overthrow him.

Imagine if the history could have been written as

After the Castro socialist government came to power on January 1, 1959, Castro made overtures to the United States, with the Eisenhower administration advising of its misgivings about a Socialist nation on the doorstep, but reassured by Castro's commitment to trade as usual, military co-operation and maintenance of property rights for US businesses and individuals in Cuba."