The US Senate on Thursday unanimously approved harsh new economic sanctions on Iran, dismissing warnings that they risked fracturing global unity on isolating Tehran over its alleged nuclear weapons program.
Lawmakers voted 100-0 to include the measure, which aims to cut off Iran's central bank from the global financial system, in a must-pass annual military spending bill expected to pass by late in the day.
The measure, crafted by Democratic Senator Robert Menendez and Republican Senator Mark Kirk, calls for freezing US-based assets of financial institutions that do business with the central bank, including foreign central banks that do so for the purposes for buying or selling petroleum or related products.
"This is the maximum opportunity to have a peaceful diplomacy tool to stop Iran's march to nuclear weapons," said Menendez.
"This is the right amendment, at the right time, sending the right message in the face of a very irresponsible regime," Kirk said.
The vote came after an 11th-hour push from US President Barack Obama's administration to convince impatient lawmakers to defeat the measure.
US officials have warned that depriving global markets of Iranian exports could send oil prices sharply higher, handing Tehran a windfall at a time when it has struggled to cope with painful international economic sanctions.
To address that concern, Kirk and Menendez's measure says the sanctions would only apply if Obama determines that there is sufficient oil from other producers to avoid disrupting global markets, and enables him to delay them if he determines that to be vital to US national security interests.
Senate passage of the underlying military spending bill would trigger negotiations with the House of Representatives to blend the chambers' rival versions of the bill into a compromise to be sent to Obama.
Earlier, Undersecretary of State for Political Affairs Wendy Sherman and Treasury Undersecretary for Terrorism and Financial Intelligence David Cohen warned the plan risked alienating key allies and inadvertently lining Iran's pockets.
"We all agree with the impulse, the sentiment, the objective, which is to really go at the jugular of Iran's economy," Sherman said in a frequently contentious hearing of the Senate Foreign Relations Committee.
"But there is absolutely a risk that, in fact, the price of oil would go up which would mean that Iran would, in fact, have more money to fuel its nuclear ambitions, not less," she said.