The first requirement for such a "deepening" was to recognize the multidimensional nature of power in the world: there was no single index by which the influence of states could be measured. Nuclear weapons , given the constraints on their use in an approaching era of parity , were of decreasing practical utility . Kissinger liked to point out that in no crisis since 1962 had the strategic balance determined the outcome. Vietnam had amply demonstrated the limits of conventional military force applied under constraints imposed by public opinion and the dangers of escalation. Ideology was proving to be a feeble force when arrayed against the compulsions of nationalism; territory bore little relationship to political influence; economic strength seemed at times to have little to do with any of these. And, underlying all of these complexities, there was the increasing importance of psychology: the perception of power had become as important as power itself.