The two credibility problems (credibility of nuclear deterrence against conventional attack and credibility of USA guarantees for Europe) add up to one large credibility problem which serves to reinforce each separate problem. This creates regional crisis instability; and may create a temptation to engage in low-key 'probes' so as to assess the seriousness of commitments made within the framework of extended deterrence. The question whether there can be such a thing as a 'limited nuclear war', not necessarily escalating into an all-out nuclear war, is extremely controversial. There is at least some likelihood that the 'tactical' use of nuclear weapons would inadvertently trigger a full-scale nuclear exchange. Very serious risks of miscalculations emerge in third world regions, where the two major powers have made a multitude of poorly defined commitments in the sense of extended (mainly conventional) deterrence.
2. Perhaps - as a growing school of thought in international relations theory argues - the precarious stability of a standoff is the best most regions can manage. But the mounting tensions between India and Pakistan should give pause. Stable deterrence is easy in theory, extraordinarily demanding in practice.