"Like atomic weapons, the bank's powers to print money and buy securities are best held in reserve as a deterrent, even if their use would not wreak destruction on a comparable scale.
Having to use them to defend a country or a policy objective could cause unintended damage and expose fatal weaknesses in the political will to sustain the action.
European Central Bank President Mario Draghi seemed to borrow from the Cold War lexicon of deterrence in July when he told financial markets that the ECB would do "whatever it takes to preserve the euro. And believe me, it will be enough.""
