- Huthi political commander Mohamed Ali al-Huthi in a tweet said the US move was "to be condemned, and we have the right to respond".
SANAA: Yemen's Huthis were defiant Monday after the United States moved to brand the Iran-backed rebels as terrorists, a last-ditch move under President Donald Trump that aid groups warned could tip the country into famine.
Unless Congress blocks the decision, the Huthis will be blacklisted on January 19 -- one day before the inauguration of President-elect Joe Biden, whose aides had hoped to mount a fresh push to end Yemen's devastating six-year-old war.
Huthi political commander Mohamed Ali al-Huthi in a tweet said the US move was "to be condemned, and we have the right to respond".
"The Yemeni people don't care about any designation from Trump's administration as it is a partner in killing Yemenis and starving them."
Iran's foreign ministry spokesman Saeed Khatibzadeh also condemned the US announcement and charged that "it's likely the bankrupt US government will do further damage to its reputation" in Trump's final days in office.
The decision announced by US Secretary of State Mike Pompeo could complicate Biden's promised efforts to restart diplomacy with Iran and to reassess Washington's alliance with Saudi Arabia, which has led a bloody offensive in its impoverished southern neighbour.
The designations aims to hold the rebel movement "accountable for its terrorist acts, including cross-border attacks threatening civilian populations, infrastructure and commercial shipping," Pompeo said Sunday.
The Huthis have "led a brutal campaign that has killed many people, continues to destabilise the region and denies Yemenis a peaceful solution to the conflict in their country".
The Yemeni government welcomed the announcement, saying the Huthis deserved it for their "continuous efforts to prolong the conflict and cause the world's worst humanitarian crisis".
Pompeo also designated as terrorists three leaders of the movement, including their chief Abdul Malik al-Huthi.
He pointed to a December 30 attack on an airport in Yemen's second city Aden, which killed 26 people and was blamed by the Saudi-backed government on the Huthis.
The Huthis control much of Yemen, including the capital Sanaa, and are already under US sanctions.
The designation is expected to scare away outside actors from many transactions with Huthi authorities, including bank transfers and buying food and fuel, for fear of US prosecution.
Aid groups have warned Pompeo against the blacklisting, saying they have no option but to deal with what is the de facto government in northern Yemen.
"The US government must ensure that any sanctions do not block food, fuel and medicines from entering a country already in the middle of a full-blown humanitarian catastrophe," warned the Norwegian Refugee Council.
Pompeo insisted that the State Department was "planning to put in place measures" to reduce the impact on humanitarian work and imports into Yemen.
Trump's administration has been ramping up pressure on Iran, hoping to make it more difficult logistically and politically for Biden to ease sanctions as he seeks a return to a nuclear deal.
US officials and analysts say Iran has armed the Huthis, but some experts question the extent of cooperation and see Tehran primarily as interested in bogging down Saudi Arabia, whose brutal air campaign has included strikes on civilian targets.
Tens of thousands of people, mostly civilians, have been killed and millions displaced in Yemen's war, with most of the nation dependent on some form of aid to survive.
Analysts warn of disastrous consequences after the UN World Food Programme said in December that malnutrition had reached record levels, narrowing the window of opportunity to prevent a famine.
Peter Salisbury, senior Yemen analyst at the International Crisis Group, said the designation "risks collectively punishing all Yemenis by precipitating a famine while doing little to hurt the Huthis other than pushing them closer to Iran".
"If the impact of this designation is half as bad as has been predicted it is millions of ordinary Yemenis who are struggling to eat who will pay the price, while already distant prospects of peace slip away."