The United States and European Union have imposed tough sanctions on Iran that have weakened its economy. But Tehran has found ways to bypass the penalties, such as Turkey's use of gold to pay for Iranian natural gas imports.
The Menendez-Kirk measure would allow the president to impose sanctions in cases of the sale or transfer of precious metals, targeting efforts by Iran to circumvent the penalties.
Mark Dubowitz, a sanctions expert and executive director of the Foundation for Defense of Democracies, said there is strong bipartisan support for intense sanctions, with the goal of pushing the Iranian economy to the brink of economic collapse.
Only then "can the central thesis of the administration's sanctions policy be fairly tested: That crippling economic pressure will break the nuclear will of Iran's supreme leader and his Revolutionary Guards and lead them to meet their obligations under international law," Dubowitz said.
The president has 90 days from the legislation's enactment to act. The bill does include the authority to waive the sanctions based on national security.