In fact, bank regulators in the United States took the position of requiring a bank to follow the set of rules (Basel I or Basel II) giving the more conservative approach for the bank. Because of this it was anticipated that only the few very largest US banks would operate under the Basel II rules, the others being regulated under the Basel I framework. Basel III was developed in response to the financial crisis; it does not supersede either Basel I or II[clarification needed] but focuses on different issues primarily related to the risk of a bank run.[citation needed]