Sentence:  During the next five years <WSD>liberal</WSD> leaders in the United States sank in the cumulative confusion attendant upon and manifested in a negative policy of Containment - and the bitterest irony - enforced and enforceable only by threat of a weapon that we felt the greatest distaste for but could not abandon : 
Meaning of the word marked with <WSD> tags:  having political or social views favoring reform and progress