The war in Yemen is escalating and becoming more dangerous. The Yemeni people are facing a humanitarian catastrophe. Unlike in Syria, the United States has significant leverage to halt the war and the suffering. Unfortunately, the frivolous override by Congress of President Barack Obama's veto of the Justice Against Sponsors of Terrorism Act has made using American leverage harder at this critical juncture. But Obama needs to act.

The Saudi-led coalition bombing of a funeral in Sanaa last weekend that killed over 140 mourners and wounded hundreds more has set off a wave of retaliation by the Yemeni rebels who control most of northern Yemen. The rebel alliance of Zaydi Shiite Houthis and followers of former President Ali Abdullah Saleh fired missiles at an American destroyer in the Red Sea. The rebels have long argued that American military, logistical and intelligence support for the Saudi coalition makes Washington a co-belligerent. The Oct. 13 cruise missile strikes against rebel radar sites — absolutely necessary to protect our ships in the strategic waters — will only add to the anti-American narrative.

The rebels have also fired at least one surface-to-surface missile at Taif, a Saudi city near Mecca. They have fired dozens of other missiles and rockets at Saudi border towns and at coalition garrisons in southern and eastern Yemen. They appear to have an unlimited supply of munitions and missiles. Sooner or later, one missile will cause a disaster.

The big beneficiary of the war is Iran. It provides the rebels diplomatic support and limited military assistance. In return, it bogs down the Saudis, Emiratis and its other Gulf enemies in a quagmire in Yemen that is expensive in lives and treasure, when oil prices are depressing their economies at home. Tehran is all too happy to fight to the last Yemeni.