Basically the same criteria United has compared to the others countries: - a large assets backing the money ( the us economy) -A large debt market that can be

Basically the same criteria United has compared to the others countries: - a large assets backing the money ( the us economy) -A large debt market that can be traded easily ( t-bills ) -A safe economic environment -A protection system for any foreign investors. No country expect the us offers those conditions. Europe debt is too fragmented, China controls his currency, and Japan is not big enough. . Russia made the move because the rouble was back by their natural resources. In India case, I m very surprised by this move and some technicals requirements would be needed.