But the fragile peace initiative has stalled, and the Houthis resumed attacking Saudi Arabia over the past several weeks in what it said was retaliation for the Saudis’ failure to curtail the violence.

Houthi drones targeted Saudi drone facilities at another airport on Sunday, a Houthi television channel said, and Saudi air defense systems have intercepted several Houthi missile and drone attacks in the last month, the official Saudi Press Agency said.

A Houthi attack on a Saudi oil pipeline last month forced the Saudis to shut the pipeline temporarily, soon after a mysterious sabotage attack damaged four oil tankers, two of them Saudi, outside the Emirati port of Fujairah.

The Houthi attacks have caused few casualties. The attack on the airport on Wednesday was one of the worst Houthi attacks on Saudi soil yet.

Because of Iran’s support for the Houthis, the Saudis portray the conflict as a proxy war between Iran and its regional enemies, Saudi Arabia and the United Arab Emirates. But most analysts say Iran does not directly control the Houthis; instead, they say, it is the most independent of the nonstate groups that receive some degree of Iranian financing and cooperation, a network that also includes Hezbollah, a Lebanese political and military group.

The Saudis first deployed aircraft and troops to attack the Houthis after the group seized Sana from the Saudi-backed government in 2015. Now, after more than four years of fighting, Yemen has been consumed by parallel political, humanitarian and health crises. The peace talks have stumbled. Millions of people are edging closer to famine. A resurgence of cholera has infected more than 364,000 people this year.

For a moment last month, it looked as if the Yemen conflict might have a period of calm. In a major step toward carrying out a partial cease-fire the United Nations brokered in Stockholm in December, the Houthis unilaterally withdrew from three strategic ports on the Red Sea, including Hudaydah, a crucial channel for humanitarian aid.