United States Secretary of State Mike Pompeo on Tuesday called on all participants to end hostilities in Yemen and said that United Nations-led negotiations to end the civil war should begin next month.

“The time is now for the cessation of hostilities, including missile and UAV [unmanned aerial vehicle] strikes from Houthi-controlled areas into the Kingdom of Saudi Arabia and the United Arab Emirates,” Pompeo said in a statement. “Subsequently, coalition air strikes must cease in all populated areas in Yemen.”

A civil war has engulfed the country after Iranian-backed Houthi rebels captured large areas, including the capital Sana’a. The Saudi-led coalition, backed by the US, has been fighting the rebels since 2015.

“Substantive consultations under the UN Special Envoy must commence this November in a third country to implement confidence-building measures to address the underlying issues of the conflict, the demilitarisation of borders, and the concentration of all large weapons under international observation,” said Pompeo.

US Secretary of Defence James Mattis earlier called on all involved parties to agree to a ceasefire “in the next 30 days”, CNN reported.

“Thirty days from now we want to see everybody around a peace table based on a ceasefire, based on a pullback from the border and then based on ceasing dropping of bombs that will permit the [UN] special envoy, Martin Griffiths – he’s very good, he knows what he’s doing – to get them together in Sweden and end this war,” Mattis said at an event in Washington.

Pompeo said ending hostilities would mitigate the humanitarian crisis in the country, which is staring at its worst famine in a century. The UN’s Humanitarian Coordinator for Yemen, Lise Grande, told the BBC earlier this month that 12 million to 13 million civilians could potentially starve to death if coalition airstrikes are not urgently halted.

“It’s a very welcome recognition that current policy is failing and needs urgently to be changed to focus on a diplomatic solution,” he said.

The UN in September described Yemen as “the world’s worst humanitarian crisis”, with close to 75% of its population requiring some form of humanitarian assistance and protection.

International Rescue Committee President David Miliband described Pompeo’s statement as “the most significant breakthrough in the war for four years”.