Is the sense of responsibility soldiers feel toward each other irrational? ... It's flukish luck, but you feel responsible. The guilt begins an endless loop of counterfactuals thoughts that you could have or should do otherwise, though, in fact, you did nothing wrong.
The italicized word or phrase <em>a three-pronged </em>(if this is italicized, we cannot possibly know) is attributive, as it is an adjective to describe the plan.