The US on Thursday imposed sanctions on Yemen's Houthi rebels as officials voiced exasperation that the Iranian-backed insurgents have kept up a military campaign.
President Joe Biden's administration – which has used sanctions more sparingly than the team of former president Donald Trump – also removed sanctions on several former Iranian officials, saying it was acknowledging changes in behaviour.
The Treasury Department said it was imposing sanctions on several people, including Said Al Jamal, a Houthi supporter who has reportedly run a smuggling network out of Iran, illicitly selling oil to benefit the insurgents.
Secretary of State Antony Blinken said the department was hoping to exert pressure on the Houthi rebels to end their offensive launched in February on the city of Marib, the last significant pocket of government-held territory in the north.
"It is time for the Houthis to accept a ceasefire and for all parties to resume political talks," Mr Blinken said in a statement.
"The United States will continue to apply pressure to the Houthis, including through targeted sanctions, to advance those goals," he said.
In one of its first actions after coming into office, the Biden administration removed a last-minute designation by Mr Trump naming the Houthis a terrorist movement.
The move came in response to fears from aid groups that they would need to pull out of Yemen as they are obliged to deal with the Houthis, who are effectively the governing force across vast areas of the country, including the capital of Sanaa.
The Biden administration has ramped up diplomatic efforts to address the humanitarian crisis in Yemen, which the US considers the worst in the world, and has distanced itself from a devastating air campaign being carried out by neighbouring Saudi Arabia.
Mr Biden has also sought to re-enter a nuclear accord with Iran which Mr Trump withdrew from in 2018.
Indirect talks in Vienna have been held up by Iran's insistence on a complete removal of sanctions.
The Treasury Department said it would remove sanctions on three former Iranian officials, including former National Iranian Oil Company chief Ahmad Qalebani.
"These delistings are a result of a verified change in behaviour or status on the part of the sanctioned parties and demonstrate the US government's commitment to lifting sanctions in the event of a change in behaviour or status for sanctioned persons," the Treasury Department said.
State Department spokesman Ned Price said the move was not linked to the nuclear deal talks in Vienna.
Critics of US sanctions policy have said that those who are sanctioned have little recourse to leave the blacklist, even if they address concerns.