Yemen’s foreign minister appealed Monday for Gulf Arab neighbors to launch military strikes against Shiite rebels who are threatening to overrun the last stronghold of the Western-allied government as the country sinks further toward full civil war.

Although Saudi Arabia and its Persian Gulf partners are fearful of spillover from Yemen’s collapse, they have given no indication of consensus on possible intervention and appear unlikely to quickly mobilize their joint military command.

The call for help reflects the increasing desperation of forces loyal to President Abed Rabbo Mansour Hadi as they try to hold off advances on Yemen’s second-largest city, Aden, by powerful insurgents known as Houthis and believed to be backed by Shiite power Iran.

The gains by the Houthis, who already control the capital Sanaa, are part of a wider unraveling in Yemen that also includes competing battles among tribal factions, a branch of the terror organization al-Qaida and cells appearing to pledge loyalty to the Islamic State.

A group claiming to be a wing of the Islamic State said it carried out twin suicide bombs on Shiite mosques in Sanaa on Friday, killing as many as 137 people. American officials and others, however, have questioned whether the Islamic State has a significant foothold in Yemen.

The deteriorating security situation led U.S. officials last week to pull out the remaining American presence, including 100 special operations troops. U.S. forces once relied on cooperation with Hadi’s government for drone strikes and other measures against Yemen’s al-Qaida group.

Britain has also evacuated its last special forces from Yemen, the Reuters news agency reported Monday, citing an official familiar with the decision.

In response to the Western exits, Yemen’s foreign minister Riyadh Yaseen reached out to the region’s Saudi-led military bloc for intervention.

“They’re expanding in territory, occupying airports and cities, attacking Aden with planes . . . gathering their forces,” Yassen said in an interview with Al Jazeera.

In separate comments to the pan-Arab newspaper al-Sharq al-Awsat, Yassen said he has made appeals directly to the Gulf Cooperation Council, or GCC, a six-nation alliance anchored by Saudi Arabia.

Britain’s foreign secretary, Philip Hammond, said Monday that his nation was holding talks with the United States and Saudi Arabia on how to bolster the besieged government in Yemen.

“None of us wants to see military action,” Hammond added after talks with Saudi leaders.

But Saudi Foreign Minister Saud al-Faisal vowed that Arab states would “take the necessary measures to protect the region from aggression” – an apparent reference to Iran.

Saudi Arabia views Iran as its chief regional rival and considered the expansion of Houthi power in Yemen as a worrisome threat on its doorstep.

Deploying the gulf military force, known as Peninsula Shield, would pull Saudi Arabia and other nations directly into Yemen’s conflict and test pledges by gulf leaders to show more resolve in tackling regional hot spots.

In 2011, Saudi forces crossed into Bahrain to help the embattled monarchy amid Arab Spring-inspired protests. More recently, warplanes from the United Arab Emirates have joined in U.S.-led airstrikes against the Islamic State.

On Saturday, a senior GCC foreign policy official, Khalid Suleiman al-Jarallah, said it was not yet clear whether the Peninsula Shield force “will or will not” intervene in Yemen.

Meanwhile, troops loyal to Yemen’s president Hadi sought to turn back offensives by Houthi fighters in Aden on Yemen’s coast. Houthi forces on Sunday claimed control of the country’s third-largest city, Taiz.