The US Treasury Secretary Janet Yellen says Washington is mulling over new ways to strengthen its sanctions against the Islamic Republic. 

Yellen said on Thursday the United States was looking at ways to increase the efficacy of its sanctions regime, acknowledging that the punitive measures had not resulted in the behavioral or policy changes Washington seeks from Tehran.

"Our sanctions on Iran have created real economic crises in the country, and Iran is greatly suffering economically because of the sanctions ... Has that forced a change in behavior? The answer is much less than we would ideally like," Yellen told lawmakers in a hearing.

She did not specify what behavioral change Washington was expecting from Tehran, nor did she elaborate on the new ways. 

Critics of crippling economic sanctions imposed by Trump administration since 2018 and largely maintained by the Biden administration, argue that Iran’s behavior has not changed as it has accelerated its nuclear program and continues to sow instability in the region.

Supporters of the sanctions say that the Iranian regime is facing a serious financial crisis, which impacts its ability to pursue its military and malign activities. They also argue that sanctions take time to have a behavioral impact, citing Russia’s continued aggression in Ukraine despite Western sanctions.

Although the Biden administration has continued issuing new sanctions against certain Iranian entities and individuals for their role in acquiring nuclear technology or money laundering, Iran has increased it oil exports since 2021.