For the United States, dealing with Iran's clerical leaders has never been for the faint of heart. But a year after massive protests following the death of Mahsa Amini, Tehran has become even more toxic for Washington.

President Joe Biden's Republican critics have savaged him for agreeing, nearly on the anniversary of the uprising, to a deal that will unfreeze $6 billion in Iranian oil revenue to bring home five Americans who had been imprisoned.

Officials and diplomats say the U.S. administration sees little alternative to engagement, with new talks possible on Iran's contested nuclear program, but few expect Biden to invest political capital to reach any substantive new agreement with the hostile state and arch-foe of Israel.