Sentence:  It occurred to me that you might be interested in some thoughts which I expressed privately in recent years , in the hope of clearing up a certain confusion in the public mind about what foreign policy <WSD>is</WSD> all about and what it means , and of developing a certain compassion for those who are carrying such responsibilities inside Government . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)