SANAA    -    Saudi Arabia and Yemen’s Iran-backed rebels are holding indirect, behind-the-scenes talks to end the devastating five-year war in Yemen, officials from both sides have told The Associated Press.

The negotiations are taking place with Oman, a Gulf Arab country that borders both Yemen and Saudi Arabia , as mediator. Oman has positioned itself as a quiet mediator in the past and in a possible sign the back-channel talks could be stepping up, Saudi Deputy Defense Minister Prince Khalid bin Salman arrived in Muscat on Monday.

The two sides have communicated via video conference over the past two months, according to Gamal Amer, a negotiator for the Yemeni rebels known as Houthis. They have also talked through European intermediaries, according to three Houthi officials. Yemen remains a divided country. The Iran-backed Houthis have controlled the capital, Sanaa, and much of the north since 2014. The Saudi-led military coalition, which entered the war in 2015, is fighting on behalf of Yemeni President Abed Rabbo Mansour Hadi and his internationally recognized government.

The Oman-mediated talks began in September, after a Houthi-claimed drone struck a key crude processing plant in Saudi Arabia — the world’s largest — and dramatically cut into global oil supplies. The United States blamed Iran, which denied involvement. The attack laid bare the vulnerability of Saudi Arabia’s oil installations and appears to have propelled Riyadh toward negotiating an end to the increasingly costly war. The kingdom has also faced a growing backlash against its role in the Yemen war, including from the U.S. Congress.

The current talks focus on interim goals, such as re-opening Yemen’s main international airport in Sanaa, shut down by the Saudi-led coalition in 2016. Also under discussion is a buffer zone along the Yemen-Saudi border in areas under Houthi control.

Abu Bakr al-Qirbi, a former Yemeni foreign minister, told the AP from Oman that the Saudis’ main concerns include dismantling the Houthis ballistic and drone capabilities and the kingdom’s border security. The Saudis are looking for assurances the Houthis will distance themselves from Shiite power Iran, the Sunni kingdom’s archrival. Riyadh has long feared the Houthis could establish an Iranian presence along the Saudi-Yemen border.

These talks could pave the way for more high-profile negotiations early next year, said one of the Houthi officials. All officials, with the exception of Amer and al-Qirbi, spoke on condition of anonymity because they were not authorized to talk to reporters on backchannel negotiations.