Civilians ordered to leave Yemen's Saada province ahead of Saudi strikes

Saudi authorities warned all civilians to leave Yemen's northwestern Saada region, which borders the kingdom, by sunset Friday as it threatened a harsh response to the Houthi rebel shelling of Saudi frontier towns earlier this week.

Mortar and rocket salvos fired from Saada killed eight people in the Saudi city of Najran on Thursday as Houthi forces struck a Saudi air defense site near the city.

In response, Saudi-led warplanes bombed targets in Saada province, a bastion of Houthi rebels, Friday. Riyadh then announced a five-day humanitarian cease-fire to begin May 12, conditioned on Houthis agreeing to the pause.

Saudi state television channel Al Ekhbariya said the whole of the arid, mountainous province would become a military target from Friday evening, hinting at an escalation in the Saudi-led coalition's six-week-old intervention in Yemen's civil war.

General Ahmed al-Asiri, the coalition’s military spokesman, said leaflets had been dropped in the Old Saada district urging residents to leave by 7 p.m. local time Friday.

“Our work now is reaching those [Houthis] who planned those attacks and who are hiding in Saada, and the places where the militias are,” Asiri said. “Our military operation will be longer and harsher, and will go after all Houthi commanders.”

The coalition aims to reverse the Shia Houthis cross-country advances — seen by Saudi Arabia, the world's top oil exporter and arch-regional rival of Iran, as a security threat — and restore President Abd-Rabbu Mansour Hadi in power. Saudi Arabia has accused Iran of supporting the Houthis militarily — a charge Iran has denied.

Later on Friday, Saudi Foreign Minister Adel al-Jubeir announced the planned five-day humanitarian truce "subject to renewal if it works out" — if Houthi forces agree to the pause.

"We hope the Houthis will come to their senses and realize the interests of Yemen and the Yemeni people should be the top priority for everyone," Jubeir told a news conference with U.S. Secretary of State John Kerry in Paris.

"The requirements are first and foremost that there is a commitment by the Houthis and their allies ... to abide by this cease-fire," he said. "This cease-fire will [apply] throughout Yemen, or nowhere in Yemen."

International concern about the humanitarian situation has grown as the airstrikes have killed more than 1,300 people, sent others fleeing from their homes and wrecked infrastructure, causing shortages of food, medicine and fuel.

"It is critically important that all countries are able to send as much relief, as efficiently, as quickly to as many Yemenis as possible," Jubeir added.

Kerry said such a cease-fire would open the door to the possibility of peace talks. He cautioned, though, that a truce "is not peace" and said it was important that Yemeni leaders tried to reach a lasting political settlement.

"They are going to have to make tough choices more than just a cease-fire because even the most durable of cease-fire is not a substitute for peace," he said.

Al Jazeera and wire services