Story highlights

NEW: Saudi ambassador says Iran is interfering in Yemen, other countries

Saudi adviser says the coalition controls the country's airspace

Houthi leader says rebels will escalate response if airstrikes continue, make Yemen a grave for Saudis

CNN  — 

Saudi and allied warplanes struck rebels in Yemen on Thursday, with Saudi Arabia threatening to send ground troops and inserting itself into its southern neighbor’s civil war, potentially opening up a broader sectarian conflict in the Middle East.

The swift and sudden action involved 100 Saudi jets, 30 from the United Arab Emirates, 15 each from Kuwait and Bahrain, 10 from Qatar, and a handful from Jordan, Morocco and Sudan, plus naval help from Pakistan and Egypt, according to a Saudi adviser.

The Egyptian state news agency on Thursday quoted Egypt’s Foreign Ministry as saying Egypt’s support also could involve ground forces.

What do those countries have in common? They’re all predominantly Sunni Muslim – in contrast to the Houthi rebels, Shiite Muslims who have taken over Yemen’s capital of Sanaa and on Wednesday captured parts of its second-largest city, Aden. The Saudis consider the Houthis proxies for the Shiite government of Iran and fear another Shiite-dominated state in the region.

“What they do not want is an Iranian-run state on their southern border,” CNN military analyst Lt. Col. Rick Francona said of the Saudis.