Sentence:  But because of the peculiar nature of the military situation in Laos , the Soviet leader must <WSD>be</WSD> tempted to let things ride - a course that would appear to cost him little on the spot , but would bog Washington in a tactical mess . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)