CAIRO (AP) — A leading aid organization on Monday warned that U.S. Secretary of State Mike Pompeo's move to designate Yemen’s Iran-backed Houthi rebels as a foreign terrorist organization would deal another “devastating blow" to the impoverished and war-torn nation.

In his announcement late Sunday, Pompeo pledged that U.S. measures would help absorb the impact on aid groups and allow humanitarian assistance to continue to flow to the Arab world's poorest country.

The Norwegian Refugee Council, one of the main humanitarian agencies active in Yemen, said the designation and Pompeo's planned sanctions on the Houthis “will hamstring the ability of aid agencies to respond” to the humanitarian needs of millions of Yemenis.

“Yemen’s faltering economy will be dealt a further devastating blow,” said Mohamed Abdi, the group's director for Yemen. “Getting food and medicine into Yemen — a country 80% dependent on imports — will become even more difficult.”

Relief organizations have long warned that sanctions could prove catastrophic for efforts to help starving Yemeni civilians caught in the conflict between the Houthis and the Yemeni government, backed by a Saudi-led coalition which has been waging war against the rebels.

“The United States recognizes concerns that these designations will have an impact on the humanitarian situation in Yemen,” Pompeo said in a statement. “We are planning to put in place measures to reduce their impact on certain humanitarian activity and imports into Yemen.”

Those measures will include the issuance of special licenses by the U.S. Treasury to allow American aid to continue to flow to Yemen and for humanitarian organizations to continue to work there, he said.

Yemen, a country on the tip of the Arabian Peninsula, is the stage of the world's worst humanitarian disaster after more than six years of a grinding conflict that has left the majority of the country's nearly 30 million people in need of humanitarian aid. The war has killed more than 112,000 people so far.

The conflict started in 2014 when the Houthis overran the north and the capital, Sanaa. The following year, the Saudi-led coalition intervened to wage war on the Houthis and to restore President Abed Rabbo Mansour Hadi’s government to power.