Saudi warplanes struck military bases that had been seized by Houthi rebels in Yemen, crippling the air force in a U.S.-backed campaign that has led to fears of a proxy war among the Middle East’s big powers.

As weekend airstrikes blunted their expansion into southern Yemen, the Iranian-backed rebels suffered a political setback: Their most powerful patron at home, former PresidentAli Abdullah Saleh, called for a truce and peace talks with his Saudi-backed rival.

The rebels continued to battle government forces on Sunday, with no end in sight to the weeks of fighting. The chaos forced the U.S. military this month to withdraw its counterterrorism forces from a country on the front lines of the global war with al Qaeda—a group at odds with both Yemeni factions but not involved in their current fray. […]