Sentence:  He may support China ( but he won n't ) ; he may break with China ( which would <WSD>be</WSD> infernally difficult and perhaps disastrous ) , or he may succeed , by all kinds of dangerous concessions , in persuading China to be patient . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)