"The Asia Infrastructure Investment Bank is positioning itself as an Asia-centric alternative to the World Bank and International Monetary Fund, even though the head of the World Bank on Tuesday tried to cast the AIIB as a partner, not a rival. However, some prominent U.S. voices recently have been expressing alarm both at the AIIB's growth, and its ability to attract U.S. allies even though the Obama administration has been seeking to discourage membership. The U.S. holds the largest voting bloc in the IMF/World Bank structure, but has not signed on to the China effort. With the addition of Iran and the United Arab Emirates, the roster of prospective AIIB members has grown to 35," reports CNBC.