UNITED NATIONS (AP) — The U.N. chief and top officials urged the United States on Thursday to reverse its decision to declare Yemen’s Iran-backed rebels a terrorist group to prevent massive famine and death in the conflict-torn Arab nation — but the Trump administration in its final days stood by its action.

The U.S. deputy ambassador, Richard Mills, told the Security Council the U.S. has listened to warnings of the terrorist designation's humanitarian impact and will take measures to reduce the impact on aid deliveries and commercial imports.

“But we do believe that this step is the right move forward to send the right signal if we want the political process to move forward,” he said.

In 2014, the rebel Houthis overran the capital, Sanaa, and much of Yemen’s north, driving the government into exile. A U.S.-backed, Saudi-led coalition intervened the following year to try and restore the internationally recognized government, but years of U.N. efforts to get both sides to agree to a cease-fire and start peace negotiations have not succeeded.

The conflict has been disastrous for Yemen, the Arab world’s poorest country, killing more than 112,000 people, creating the world’s worst humanitarian crisis, and wrecking infrastructure from roads and hospitals to water and electricity networks.

U.S. Secretary of State Mike Pompeo declared the Houthis a “foreign terrorist organization” late Sunday. The designation takes effect Jan. 19, President Donald Trump’s last full day in office before Joe Biden is inaugurated president.

U.N. humanitarian chief Mark Lowcock warned the Security Council that the U.S. designation will likely lead to a “famine on a scale that we have not seen for nearly 40 years.”

Data show that 16 million of Yemen’s 30 million people will go hungry this year, he said. “Already, about 50,000 people are essentially starving to death. ... Another 5 million are just one step behind them.”

Lowcock said Yemen imports 90% of its food, nearly all purchased through commercial channels, so aid shipments cannot be enough to stave off hunger.

Stressing that the designation is already seeing companies pull back from Yemen, Lowcock warned that famine will not be prevented by the measures the United States has promised to introduce so some humanitarian aid and imports can continue to reach Yemen.

World Food Program Executive Director David Beasley told the council the Nobel Peace Prize-winning agency was forced to reduce the number of Yemenis receiving aid from 13 million to 9 million, and then to cut rations in half because of a lack of funding.

Starting Feb. 1, “we will have to cut rations to 25%” because money is running out, he added.

Beasley predicted that the U.S. action, coupled with the funding crisis, will create “a catastrophe” and leave 24 million of the 30 million Yemenis “struggling to eat” and get fuel and medicine.

“In 2020, the United States stepped up to WFP with $3.75 billion of support and I’m very grateful for that,” he said. “But this designation — it needs to be reassessed, it needs to be reevaluated, and quite frankly it needs to be reversed.”

Beasley said WFP needs $860 million to avert famine in Yemen for the next six months, and “we don’t even have half that.”

He said the Gulf Arab states — singling out Saudi Arabia — “need to pick up the humanitarian financial tab for this problem." If they don’t, he warned, donors will take money from other countries where it's desperately needed, “which means we’re going to have famine in many, many other countries.”

Martin Griffiths, the U.N. special envoy for Yemen, backed Lowcock’s assessment that the U.S. designation “would contribute to famine in Yemen and thus should be revoked."

In addition, he said, “We fear that there will be inevitably a chilling effect on my efforts to bring the parties together.”

U.N. spokesman Stephane Dujarric said Secretary-General Antonio Guterres supports the calls by Lowcock, Beasley and Griffiths for the U.S. to reverse its designation, pointing to their “very passionate” and detailed remarks of the consequences on Yemenis.

On the political front, Griffiths condemned the Dec. 30 missile strike at Aden’s civilian airport targeting the newly formed Cabinet, an attack that killed more than 25 people. He said Yemen's internationally recognized government has concluded the Houthis were “behind the attack” — a charge the rebels have denied.

British Ambassador Barbara Woodward told the council the United Kingdom “assesses that it is highly likely that the Houthis were responsible for this cowardly and craven attack.”

“Only they had the means, the motive, and the opportunity for this clear and deplorable attempt to destabilize the newly formed Yemeni government,” she said.

Griffiths expressed “solidarity with the new government, which has demonstrated its resolve to stay in Aden despite the security risks to carry out its duties to the Yemeni people.”