Yemeni government fighter fires a vehicle-mounted weapon at a frontline position during fighting against Houthi fighters in Marib, Yemen March 28, 2021.

US Special Envoy for Yemen Tim Lenderking will travel to Saudi Arabia and Oman on Thursday for talks with government officials about efforts to end Yemen’s civil war, the US State Department said in a statement.

Lenderking’s “discussions will focus on ensuring the regular and unimpeded delivery of commodities and humanitarian assistance throughout Yemen, promoting a lasting ceasefire, and transitioning the parties to a political process,” the statement said.

A Saudi Arabia-led military coalition intervened in Yemen in 2015 after the Iran-aligned Houthi group ousted the country’s government from the capital Sanaa.

The civil war has created what the United Nations calls the world’s worst humanitarian crisis, with some 80 percent of the country’s population of 29 million requiring aid and 13 million facing starvation.

Since taking office in January, US President Joe Biden has made Yemen a priority and appointed Lenderking to help revive stalled UN efforts to end a conflict widely seen as a proxy war between rivals Saudi Arabia and Iran.

The battle for Yemen’s gas-rich Marib region is complicating US efforts to reach a ceasefire needed to end the war.

Lenderking “will build on the international consensus to halt the Houthi offensive on Marib, which only worsens the humanitarian crisis threatening the Yemeni people,” the State Department said.

Last week, Lenderking called the battle for the Marib region the single biggest threat to peace efforts. He said Iran’s support for the Houthi movement was “quite significant and it’s lethal.” Iran has denied supporting the Houthis.