Sentence:  Cuban S. S. R. : Whatever may have been the <WSD>setbacks</WSD> resulting from the unsuccessful attempt of the Cuban rebels to establish a beachhead on the Castro held mainland last week , there was at least one positive benefit , and that was the clear-cut revelation to the whole world of the complete conversion of Cuba into a Russian dominated military base . 
Meaning of the word marked with <WSD> tags:  an unfortunate happening that hinders or impedes; something that is thwarting or frustrating