Fierce fighting continued in recent days in Yemen, with tribal militias backed by air strikes and airborne supplies of weapons from a Saudi-led coalition managing to push Iranian-backed Shi’ite Houthi rebel groups out of several neighborhoods in the southern city of Dalea. Much of the city, which had a population of 90,000 two months ago, has been destroyed, adding to Yemen’s increasingly desperate humanitarian crisis. In related developments, a sale to Saudi Arabia of nearly $2 billion in missiles and other ammunition to replenish the stocks used in two months of air strikes in Yemen was approved by the US State Department last week, and a summit scheduled to begin on Thursday in Geneva and meant to work out a long-term cease-fire for Yemen has been indefinitely postponed.