The greatest danger posed by a nuclear Iran would be the increased likelihood of a Middle East nuclear war, Dennis Ross said.
"If Iran has nuclear weapons, the potential for nuclear war in the Middle East goes up dramatically," Ross, who retired as the White House's top Iran policy official, said during his first post-Obama administration address at the Washington Institute for Near East Policy.
The danger, Ross said, lies in the complete lack of communication between Israel and Iran, as opposed to open lines between earlier nuclear antagonists, like the United States and the Soviet Union.
"You are not going to have a stable situation where anyone can feel that they are going to wait," he said. "If there is the slightest indication that Iran is changing its readiness, can Israel wait? … The potential for miscalculation would be enormous."
Ross said President Obama was committed to preventing Iran from acquiring a nuclear weapon.
"The administration prides itself on a certain reality that it does what it says," he said, referring to Obama's making good on his promise to capture or kill Osama bin Laden.
Regarding Iran, Ross said, when Obama "says all options remain on the table, it doesn't mean that force is his first choice, but it means that that's an option that he intends to exercise."
Meanwhile, a bill agreed upon by Senate and House negotiators Monday creates more leeway for the administration to opt out of cutting off entities that deal with Iran's Central Bank, Sen. Carl Levin (D-Mich.), the chairman of the Senate Armed Services Committee and the upper body's lead negotiator, told reporters.
Cutting off Iran's Central Bank would effectively shut off the Islamic Republic's economy from Western trade. The Obama administration sought to moderate the bill, arguing that it needed leeway in order to line up support for sanctions elsewhere in the world before fully shutting out the bank.