What they say

The US position on the AIIB remains clear and consistent ... But the United States believes that there is a pressing need to enhance infrastructure investment around the world, and we believe that any new multilateral institution should incorporate the high standards that the international community has collectively built at the World Bank and at other regional development banks.

White House statement

The IMF is willing to cooperate with the AIIB as there is massive room for cooperation with AIIB on infrastructure financing.