The Obama administration has changed U.S. strategy toward Iran three times. At the administration's inception, President Obama shed the Bush administration's refusal to negotiate with Iran's government, ending support for regime change, sending flowery good wishes at Persian new year and declining to condemn that government for election fraud in 2009. This was a strategy of unconcern for the nature of Iran's government, banking instead on working with it to achieve mutual interests. Let's call that strategy detente.
The administration's second policy shift was to give up hope for progress in government-to-government channels (after remarkably little effort), and instead emphasize multilateral sanctions. In order to gain support of reluctant potential partners, the administration further dialed back U.S. policy in two areas: threat of military strikes on Iran's nuclear facilities, and condemnation of Iranian domestic policies. Even the Pentagon leadership -- civilian and military -- downplayed what could be achieved by destroying elements of Iran's programs.