Sentence:  Cuban S. S. R. : Whatever may have been the setbacks resulting from the unsuccessful attempt of the Cuban rebels to establish a beachhead on the Castro held mainland last week , there was <WSD>at</WSD> 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:  if nothing else (`leastwise' is informal and `leastways' is colloquial)