The US is building international support for a UN campaign to disrupt supplies heading for the Houthi militia in Yemen, Washington’s special envoy to the country has said.

Tim Lenderking added that the US is also considering re-designating the militia as a terrorist group.

Last week, he visited the UN Verification and Inspection Mission for Yemen, based in Djibouti on the opposite side of the Red Sea.

The mission’s focus is to inspect ships arriving in Houthi-controlled ports, to intercept weapons deliveries.

Though the UN Security Council has imposed an arms embargo, UNVIM, established in 2016, has limited means to interdict ships.

Lenderking said he is researching ways to make the mission more effective at preventing Houthi access to foreign weaponry.

The Houthis have said their Red Sea campaign is a stand of solidarity with Palestinians in the Gaza Strip.

The campaign will come to an end if a ceasefire is reached between Israel and Hamas, Houthi leaders have said.

“UNVIM is not equipped or given the mandate to do interdictions. We are working with partners to look at a change to the mandate,” Lenderking said.

“We all have to plug the holes, and that requires a different mindset and different sort of focus than simply escorting ships.”

The number of commercial ships transiting the Red Sea has halved in the past year due to the Houthi campaign. The US and UK militaries have staged a series of attacks on the militia’s positions in Yemen.

As a result, Houthi leaders are “much more careful how they are moving around,” said Lenderking. “They have altered their communications in light of the walkie talkie attacks on Hezbollah.”