There is no such thing, USD is virtual and everyone uses it. Why would the US care about Crypto? It's totally irrelevant.
+1
It would be weird that US Gov would create a coin because,1) they are against cryptos and launching a crypto currency is in conflict with the policy of supporting fiat, and, 2) this coin won't be poplar cause no one would agree to support the gov, the institute that always try to control everything