The US on Thursday imposed sanctions on Yemen's Houthi rebels as officials voiced frustration over the Iran-backed insurgents' continuing military campaign.
US President Joe Biden's administration also removed sanctions on several former Iranian officials, saying it was acknowledging their 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, selling oil to benefit the rebels.
US Secretary of State Antony Blinken said the department was hoping to exert pressure on the 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.
"The United States will continue to apply pressure to the Houthis, including through targeted sanctions, to advance those goals."
In one of its first actions in office, the Biden administration removed a last-minute move by former president Donald Trump to designate the Houthis as a terrorist movement.
Mr Trump moved after aid groups expressed fears that they would have to pull out of Yemen because they were obliged to deal with the Houthis.
The Biden administration has increased diplomatic efforts to address the humanitarian crisis in Yemen.
It has also distanced itself from the Arab coalition led by Saudi Arabia, which is fighting the Houthis at the request of the internationally recognised Yemeni government.
Mr Biden is also seeking to re-enter a nuclear accord with Iran from which Mr Trump withdrew in 2018.
Indirect talks in Vienna have been delayed 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 department said.
State Department spokesman Ned Price said the move was not linked to the nuclear talks in Vienna.
Critics of US sanctions policy have said those who have sanctions applied have few avenues to be taken off the blacklist, even if they address concerns.