Such equilibrium is stable by virtue of the mutual benefits it brings to both groups. Moreover, the more it lasts, the more it is impossible to change since both group become mutually dependant through the stock of claims and debts they have reciprocally accumulated. Any significant break, for instance, in the allocation of reserves by surplus countries, would both trigger major exchange and interest rate volatility in deficit countries and lead to significant valuation losses in surplus countries. This “financial balance of terror” is supposed to keep the system in place for a long period of time. Implicit behind this doctrine, however, is the assumption that the creditor country can live with the risk of losses on its reserves and accept that possibility as a price to pay for the success of its growth strategy. A more recent explanation is provided by the “asset shortage” theory (Caballero, 2006), which helps and explains why asymmetries in financial developments generate both payment imbalances and asset bubbles. According to the theory, the world has a shortage of liquid  4  BIS Review 76/2010  and riskless assets. Moreover, the supply of those assets is asymmetrically distributed between regions, with the US providing a large chunk of the total. Hence, there is a structural excess demand for dollar denominated securities, which sustains permanent capital inflows in the US.
It would ensure regular supply of international liquidity, but could only provide partial protection against exchange rate volatility and valuation losses. There is an important trade off, there , which is the essence of a new “Triffin dilemma” and which cannot be avoided when looking at the public supply of international liquidity, whether by one nation or within a multilateral framework.   More fundamentally, a new currency which would provide a reliable store of value would, in fact, grant its holders a collective guarantee against exchange risk. That guarantee would benefit surplus countries and would be given by deficit countries. This issue was intensely debated when the substitution account was discussed and negotiated within the IMF, more than 25 years ago. It became clear, at the time that it would not be accepted by many countries unless some explicit, binding and symmetric rules on balance of payment adjustments were agreed upon simultaneously. Most likely, those questions would be raised again today and the creation of a new reserve currency would have to be part of a broader framework. Conclusion and provisional policy lessons Looking at the next decade, one can project two alternative – and polar – scenarios for the evolution of the international financial system. First, a scenario of progressive and partial fragmentation: no significant capital account opening would occur in many parts of the world.