US Secretary of State John Kerry on Thursday announced a fresh international peace initiative for Yemen aimed at forming a unity government to resolve its 17-month-old conflict.
"This war needs to end and it needs to end as quickly as possible," Kerry said after a meeting in Saudi Arabia with Gulf counterparts, a British minister and the UN peace envoy to Yemen.
He said participants "agreed on a renewed approach to negotiations" between the Saudi-backed government and Iran-supported Shiite rebels, after three months of talks in Kuwait ended earlier in August without headway.
Those talks were suspended when the Shiite Huthi rebels and forces loyal to their ally, former president Ali Abdullah Saleh, appointed a council to govern Yemen.
Kerry outlined a plan which offers the Huthis participation in government in exchange for an end to violence and a surrender of weapons.
"This is a proposal that offers the Huthis an opportunity to have confidence in the government structure that will be put in place," he said.
The Huthis had been demanding a unity government as the first step towards resolving Yemen's war.
But the internationally backed government of President Abedrabbo Mansour Hadi wanted a rebel pullout from seized territory, including the capital Sanaa, and a surrender of weapons, as the first steps, in line with a UN Security Council resolution on the crisis.
Kerry also lashed out at Iran over alleged arms shipments to the rebels.
"The threat potentially posed by the shipment of missiles and other sophisticated weapons into Yemen from Iran extends well beyond Yemen and is not a threat just to Saudi Arabia and... the region," Kerry told reporters in the Red Sea city of Jeddah.
"It is a threat to the United States and it cannot continue."
The new push for peace will have "both a security and political track simultaneously working in order to provide a comprehensive settlement", said Kerry, adding that Gulf states had "agreed unanimously with this new initiative".
He said details would be finalised by the "parties themselves".
But the final agreement, in broad outline, would initially include the "swift formation of a national unity government with power shared among the parties".
It also calls for the "withdrawal of forces from Sanaa and other key areas", and the "transfer of all heavy weapons including ballistic missiles and launchers from the Huthis and forces allied with them to a third party".
A Saudi-led Arab coalition in March last year launched a military campaign against the Huthis as they closed in on Hadi in his southern refuge in Aden.
Anti-rebel forces subsequently regained some territory but the Huthis still hold onto other regions, including Sanaa.
More than 6,600 people, mostly civilians, have been killed since March 2015 and more than 80 percent of the population has been left in need of humanitarian aid, according to the UN.
Kerry spoke of the "staggering" humanitarian impact of the war and announced an additional $189 million in aid in response to the crisis.
If a settlement cannot be reached that respects Saudi sovereignty and security while providing Yemen's Huthi minority a role in government, "then things can only go in one direction, and that is worse in Yemen", Kerry warned.
Apart from the humanitarian crisis, the conflict has allowed an expansion of jihadists who have taken advantage of Yemen's power vacuum, he said.
Kerry said Washington was "deeply troubled" by rebel attacks on Saudi territory, where more than 100 soldiers and civilians have been killed in cross-border bombardments and skirmishes.
As the civilian death toll in Yemen climbs following the suspension of UN-brokered peace talks, the kingdom has faced rising criticism from human rights groups.
The United Nations on Thursday called for the creation of an independent international body to investigate an array of serious violations in Yemen.
In a new report, it laid out a long list of allegations of grave human rights abuses by all sides in the war.
Saudi-led coalition air strikes were suspected of causing around half of all civilian deaths, while attacks by rebel-affiliated groups were blamed for around a quarter of deaths, it said.
Saudi Foreign Minister Adel al-Jubeir, at a joint press conference with Kerry, said Riyadh had been "extremely careful and cautious" in trying to avoid non-combatant casualties.