Sentence:  Though President John F. Kennedy <WSD>was</WSD> primarily concerned with the crucial problems of Berlin and disarmament adviser McCloy 's unexpected report from Khrushchev , his new enthusiasm and reliance on personal diplomacy involved him in other key problems of U. S. foreign policy last week . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)