Yemen's Iran-backed Huthis have vowed to respond to US air strikes with escalation after the attacks killed 31 people and wounded over 100. US President Donald Trump ordered the strikes in response to the rebels' repeated attacks on shipping vessels in the Red Sea and Gulf of Aden. The Huthis have promised that the strikes 'will not pass without response', while Iran's top diplomat condemned the deaths and said the US had no authority to dictate Tehran's foreign policy. The Huthis are part of the 'axis of resistance' and have launched numerous drone and missile attacks on ships in the region.