The withdrawal of Houthi rebels from three of Yemen’s ports as part of the December 2018 ceasefire agreement should have been the basis for further talks to expand the truce to other parts of the country. But while the withdrawal was under way last week, Houthis, who are reportedly getting support from Iran, carried out a drone attack on a Saudi pipeline, and in retaliation Riyadh launched airstrikes on Sanaa, the capital city controlled by the rebels, killing at least six civilians, including children. Yemen now risks falling back to the pre-ceasefire days of conflict with fighting having broken out in parts of the government-controlled south. What makes the resumption of hostilities more dangerous is the regional angle. Tensions are on the rise in West Asia over the U.S.-Iran standoff. The U.S. had earlier warned against possible attacks by either Iran or Iran-backed militias against American interests or its allies in the region, and has deployed an aircraft carrier and a bomber squad to the Gulf. Immediately after the pipeline was attacked, the Saudis blamed Iran for ordering it, an allegation which both Tehran and the Houthis have refuted. Whether Iran was actually behind the attack or not, the incident and the subsequent Saudi airstrikes show how the Yemeni conflict is entangled with the regional rivalry between Iran and Saudi Arabia.