SANA, Yemen — The United States, which long supported Yemen’s president, even in the face of recent widespread protests, has now quietly shifted positions and has concluded that he is unlikely to bring about the required reforms and must be eased out of office, according to American and Yemeni officials. The Obama administration had maintained its support of President Ali Abdullah Saleh in private and refrained from directly criticizing him in public, even as his supporters fired on peaceful demonstrators, because he was considered a critical ally in fighting the Yemeni branch of Al Qaeda. [...] “The Americans have been...