The outgoing Trump administration’s decision to classify Yemen’s Houthi rebels as terrorists will only cause more suffering for the people of that war-torn nation, Joe Biden’s nominee for national security advisor said Saturday.

“Houthi commanders need to be held accountable, but designating the whole organization will only inflict more suffering on Yemeni people and impede diplomacy critical to end the war,” Biden’s pick for national security advisor, Jake Sullivan, tweeted.

The rebels control much of Yemen and have faced an offensive from US ally Saudi Arabia, with millions in Yemen depending on aid to survive.

Designating the Houthis a terrorist group is expected to halt many transactions with Houthi authorities, including bank transfers, paying medical personnel and for food and fuel, due to fears of US prosecution.

The designation is set to come into force on January 19 — the eve of the inauguration of Biden, whose aides had hoped to mount a fresh push to end Yemen’s six-year war.

It is also seen as complicating the incoming US leader’s promised efforts to restart diplomacy with Iran, which has links to the Houthis.

The terrorist classification has drawn criticism from aid groups, the European Union and many others over fears it will exacerbate the already dire humanitarian crisis in Yemen.

Mark Lowcock, the UN undersecretary general for humanitarian affairs, said on Thursday that exemptions to allow aid agencies to deliver supplies, as suggested by Washington, would not be sufficient to avoid a famine, adding “what would prevent it? A reversal of the decision.”