No one should doubt that President Barack Obama is prepared to use military force to prevent Iran from acquiring a nuclear weapon if sanctions and diplomacy fail, the president’s former special assistant on Iran said.

“There are consequences if you act militarily, and there’s big consequences if you don’t act,” said Ross, who in a two- hour interview at the Bloomberg Washington office laid out a detailed argument against those who say Obama would sooner “contain” a nuclear-armed Iran than strike militarily.

The administration considers the risks of permitting a nuclear-armed Iran to be greater than the risks of military action, said Ross, who last month rejoined the Washington Institute for Near East Policy, a research group.

His comments came the day after Obama’s top civilian and uniformed defense officials said that developing a nuclear weapon would cross a red line, precipitating a U.S. strike.