by ROBERT BECKHUSEN

Saudi Arabia has launched a major air campaign against Houthi rebels in Yemen. During the opening hours, Riyadh’s warplanes bombed some of the largest rebel-held air bases in the country.

These bases — and the fighter jets and helicopters parked at them — had been one of the Yemeni government’s only material advantages. For years, Yemen depended on its largely obsolete air force to carry out strikes against rebels in areas where its ground army couldn’t go.

The Houthis are a Zaidi Shia rebel group who have fought an off-and-on conflict with the Yemeni government since 2004. In 2014, the Houthis staged a massive rebellion and seized the Arabian nation’s capital of Sana’a.

The rebels have since taken several air bases.

Now it appears that much of Yemen’s air combat power is either destroyed or in rebel hands. Adel Al Jubeir, the Saudi ambassador to the United States, suggested the collapse of the Yemeni air force helped trigger the intervention.

“We have a situation where you have a militia group that is now in control or can be in control of ballistic missiles, heavy weapons and an air force,” Al Jubeir said.

During the opening hours of the Saudi offensive on March 26, warplanes from the kingdom bombed Sana’a International Airport and Al Anad air base. Sana’a airport includes a military base.

Houthi rebels captured both bases in recent months — and Al Anad in Southern Yemen merely days ago. The U.S. had just evacuated around 100 U.S. troops and Special Forces from the facility, which has served as a base for Washington’s largely-clandestine war against Al Qaeda in the Arabian Peninsula.

The rebels seized Taiz Ganed Airfield — in the city of Taiz — and Aden International Airport. Pro-government troops retook the latter. But this means that rebels are either in control or are directly threatening most of Yemen’s air bases.

The Saudi-led strikes are likely prioritizing anti-aircraft weapons, radars and aircraft on the ground. Qatar, Kuwait, Bahrain, the United Arab Emirates, Egypt, Morocco, Jordan and Sudan have joined the coalition.

It’s not clear if the Houthis can mount much of a defense with their captured fighters. But the militants have used them in a ground-attack role before.

“Shortly after [Yemeni Pres. Rabbo Mansour] Hadi fled his palace in Aden, warplanes targeted presidential forces guarding it,” Reuters reported. “No casualties were reported.”