Credibility is a dangerous and potentially misleading concept in foreign policy. It can be the logic behind escalation in a misconceived war, and it can be deployed as the last-stand argument against withdrawal. And it dubiously assumes, as in Afghanistan, that others judge our calibre and strength in general by our determination in one peripheral conflict.
Here’s what Hans Morgenthau had to say in 1965 during the Vietnam war:
‘Does not a great power gain prestige by mustering the wisdom and courage necessary to liquidate a losing enterprise? In other words, is it not the mark of greatness, in circumstances such as these, to be able to afford to be indifferent to one’s prestige?’