Saudi Arabia offered Thursday to suspend attacks in Yemen during a five-day “humanitarian pause” after appeals from Secretary of State John F. Kerry to allow greater aid into the war-battered nation.

But it was not clear when the break in the conflict could start. It hinges on whether rebel groups in Yemen agree to the conditions of the cease-fire — which Saudi official say could be extended if tensions ease.

The Saudi pledge was a boost for Kerry’s efforts to expand help for refugees and others suffering in Yemen, where a Saudi-led coalition began airstrikes in late March after rebels ousted the country’s Western-allied president.

Saudi Foreign Minister Adel al-Jubeir, speaking at a news conference with Kerry, called on the insurgents in Yemen to halt their ground operations during the proposed five-day break.

Jubeir also held out the prospect of a longer lull, saying the cease-fire could be extended if the rebels agree to abide by the “pause” and not use the halt in airstrikes to gain new territory.

“There will be a cease-fire everywhere, or there will be a cease-fire nowhere,” he said.

The United Nations and other relief agencies estimate more than half of Yemen’s people have either been driven from their homes by fighting or face shortages of water, medicine and other vital supplies.

Yemen has endured years of conflict, including U.S. drone strikes against a powerful local branch of al-Qaeda. But the country’s humanitarian crisis has sharply escalated amid the showdown between the Saudi-led coalition and rebels known as Houthis.

Houthi fighters and their allies have control of large areas of Yemen, including the capital, Sanaa. Sunni Saudi Arabia and other Persian Gulf Arab nations claim the rebels are backed by Shiite power Iran, the Sunni nations’ chief regional rival. Iran denies any direct links to the rebels but has denounced the Saudi-led airstrikes.

Kerry underscored that the cease-fire is now up to the Houthis and requires a complete quieting of arms.

“No bombing, no shooting, no repositioning of troops to achieve military advantage,” he said. “We strongly urge the Houthis and those who back them to use all influence not to miss this major opportunity.”

Late Wednesday, Yemen’s U.N. ambassador, Khaled Alyemany, sent a letter to the U.N. Security Council asking it to “quickly intervene” with ground troops to push back the rebel forces after dozens of civilians died in strikes on a crowded port where they were waiting for boats in which to escape.

Kerry, however, said there are no plans to deploy U.S. forces to Yemen.

He said he expects that more details on the possible cease-fire could emerge Friday in Paris, where Kerry will join foreign ministers of the six-nation Gulf Cooperation Council to discuss the situation in Yemen and the status of nuclear talks with Iran.

He added that aid groups also need time to coordinate strategies to bring supplies into Yemen by land, sea or air.

Jubeir said Saudi Arabia would donate $274 million for humanitarian aid to Yemeni civilians and grant a special visa status to an estimated 2 million to 3 million Yemenis who are in Saudi Arabia illegally so they can get jobs and earn money to send home to their families.

A conference is planned for May 17 in Riyadh in the search for a peaceful resolution to the conflict, but the rebels have rejected Saudi demands to reinstate Yemen’s exiled president, Abed Rabbo Mansour Hadi.

Earlier Thursday, Kerry held talks with Saudi Arabia’s King Salman and, in a sign of support for the embattled Yemeni government, met with Hadi, who has taken refuge in Saudi Arabia.

“Good to see you here in Riyadh,” said Hadi as the two men shook hands in the lobby of the al-Nasarieh guest palace.

“Hopefully, we’ll see you in Sanaa soon,” Hadi added.

“Aaah,” Kerry replied, “there’s some work to do.”

“I know, we have some work to do,” Hadi said.

“Let’s do the work,” Kerry replied, and they headed into a salon to confer.

Daniela Deane in London and William Branigin in Washington contributed to this report.

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