Creating a situation in which U.S.-Iran dialogue becomes possible -- bilaterally, or in larger forums -- poses one kind of test for Mr Obama. Putting in place a U.S. security guarantee for Saudi Arabia, Egypt, Turkey and others were he to decide on nuclear containment would pose another altogether. Neither Ayatollah Khamenei nor Mr Netanyahu can be easily outmanoeuvred. Serious groundwork will be required. A lot will ride on how urgently and effectively Mr Obama’s new team can get to work.