Treasury Secretary Steven Mnuchin signaled on Wednesday the U.S. may impose “very strong” sanctions on Iran as President Donald Trump seeks to renegotiate a multinational accord to curb the Islamic Republic’s nuclear program.

Mnuchin, testifying before a House appropriations subcommittee, said there will be “primary and secondary sanctions” against Iran, and he expects them to have a “very strong” impact on the country’s economy.

It wasn’t immediately clear whether Mnuchin was referring to a fresh round of sanctions, or the return of previous sanctions that have been waived as part of the nuclear deal.

Trump has set a May 12 deadline to improve or scrap the accord -- made by his predecessor Barack Obama -- that waived sanctions on Iran in exchange for curbs on the country’s nuclear activities. Unilateral abrogation would almost certainly trigger a diplomatic crisis between the U.S. and the other signatories -- Britain, China, France, Germany and Russia.

The Trump administration has accused Iran of fomenting instability and violence across the Mideast, and the deadline gives the White House and Congress limited time to forge legislation punishing the country for that behavior without directly ending the nuclear accord.

Trump “wants a better deal,” Mnuchin said.

This article was provided by Bloomberg News.