Washington's top diplomat said Thursday there are limits to what it would accept in any Iran deal, as an attack on a ship in the Strait of Hormuz led the UN to suspend an effort to evacuate trapped mariners. Secretary of State Marco Rubio -- in Bahrain as part of a regional tour to reassure Gulf partners hit hard by the Middle East war -- also dismissed the idea of allowing Tehran to charge fees in the strait, saying it would open the door to "total chaos".