The Biden administration plans to designate Yemen’s Houthi militia as a terrorist organisation, partly reimposing penalties it lifted nearly three years ago on the Iran-backed group whose attacks on Red Sea shipping traffic have drawn a US military response.

Beginning in mid-February, the US will consider the Houthis a “specially designated global terrorist” group, according to a US official, blocking its access to the global financial system, among other penalties. The official spoke on the condition of anonymity to discuss a policy that had not yet been officially announced.

But Biden officials stopped short of applying a second, more severe designation — that of “foreign terrorist organisation” — which the Trump administration imposed on the Houthis in its final days. The state department revoked both designations shortly after President Joe Biden took office in early 2021.

That further step would have made it far easier to prosecute criminally anyone who knowingly provides the Houthis with money, supplies, training or other “material support”. But aid groups say it could also complicate humanitarian assistance to Yemen.

The move comes as a response to, and an effort to halt, weeks of Houthi missile and drone attacks on maritime traffic off Yemen’s coast. Those attacks, which the group describes as a show of solidarity with Palestinians under Israeli bombardment in Gaza, have forced some major shipping companies to reroute their vessels, leading to delays and higher shipping costs worldwide. After issuing multiple warnings to the Houthis, Biden ordered dozens of strikes on their facilities in Yemen, although US officials say the group retains most of its ability to attack Red Sea commerce.

But the designation also reflects a careful effort to strike a balance, one that protects the flow of desperately needed humanitarian aid to the people of Yemen, who have endured famine, disease and displacement through more than a decade of civil war after the Houthis seized the country’s capital in September 2014.

US officials fear that branding the Houthis a foreign terrorist organisation could cause aid groups to stop sending supplies into Houthi-controlled areas of Yemen for fear of criminal liability or other US penalties. But even the lesser label of specially designated global terrorist groups could jeopardise US and Saudi efforts to construct a lasting peace deal to end the conflict in Yemen.