In an article, Castro said the Nobel committee decision was designed to criticize "the politics of genocide" pursued by Obama's predecessors.
"I don't always agree with decisions by this institution," Castro wrote. "But this time, I recognize that it was a positive step."
He added that many around the world thought the prize had been premature.
"But we want to see in this decision more than just an award to a US president," Castro continued. "We see in it criticism of the politics of genocide pursued by a number of past US presidents."
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Putting principles before profits
Putting principles before profits