Sana'a, Yemen - The US will once again consider Yemen's Houthi rebels a terrorist group after previously dropping the classification in 2021, according to new reports.

The imminent designation of the Houthis as a "specially designated global terrorist" entity, as reported by CNN, comes amid attacks by the group on shipping and military vessels in the Red Sea.

On Tuesday, the US military said it struck Yemen to destroy four anti-ship missiles "prepared to launch from Houthi-controlled areas," and which "presented an imminent threat to both merchant and US Navy ships in the region."

It is at least the third time in less than a week that the US has carried out strikes against the Houthis, who have repeatedly taken aim at merchant vessels in the vital Red Sea shipping lane – attacks the rebels say are in support of Palestinians being besieged by Israel in Gaza.

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The US military also said that the Houthis launched an anti-ship ballistic missile into international shipping lanes on Tuesday, and that a Maltese-flagged bulk carrier reported that it was hit but remained seaworthy.

Ina joint operation with Britain, the US targeted nearly 30 sites in Yemen with more than 150 munitions last week, while American forces later attacked a Houthi radar site in what was described as "a follow-on action" related to the previous strikes.

The designation could seriously complicate the humanitarian response in the country, battered by a civil war in which a US-backed Saudi Arabia intervened to devastating effect.