Iranian support for the Houthis in Yemen is “significant” and “lethal,” the special envoy for the country said during a US State Department briefing on Wednesday.

Tim Lenderking told lawmakers that Iran has shown no indication of wanting a constructive resolution to the conflict, adding that the US would welcome the idea of Tehran playing a positive role if the regime was willing to do so.

Following 70 cross-border attacks from Houthi-controlled areas of Yemen into Saudi Arabia last month, Lenderking said the increase in strikes on the Kingdom was a “very disturbing trend.”

He said it had been difficult to halt shipments of weapons from Iran to the Houthis, and called for assistance from the international community to prevent Iranian-made arms from reaching the militia.

“The Iranians should not get a free pass here, what they are doing is negative,” he said.

More pressure has to be put on the smuggling networks used by Tehran, Lenderking said, as more weapons on Iranian vessels needed to be captured for a display to the international community.

He added the ongoing battle for Yemen’s Marib region was the “single biggest threat to peace efforts,” while warning if hostilities were not stopped immediately it would “trigger a wave of even greater fighting and instability.”

“We are very concerned over the way Houthis govern; many of their tactics are undemocratic,” he said.  

He criticized the “harassment of aid workers and blockage of aid workers being able to carry out their projects and works,” adding: “All of this does not sound to me like a government that is devoted or committed to the Yemeni people.”

The Houthis have intensified attacks on government-controlled areas in the Marib province but have not made much progress. Abdu Abdullah Majili, a Yemeni army spokesperson, told Arab News last week that dozens of Houthis had been killed recently in failed attacks in major battlefields such as Al-Kasara and Helan, to the west of the city.

Democrat Congressman Ted Deutch echoed Lenderking’s calls for the Houthi offensive on Marib to stop. He said the militia continues to violate the “basic human rights of the Yemeni people” and that they bore responsibility for obstructing essential humanitarian assistance by manipulating fuel supplies and diverting customs revenues.

Republican Congressman Joe Wilson told the briefing that solving the humanitarian crisis and ongoing conflict in Yemen could not be done without addressing the regional threat of the “terrorist regime in Iran.”