ADEN—At least five people were killed and 34 injured in what Yemeni-government media said was a Houthi missile strike on Marib city on Wednesday night, state news agency SABA said on Friday. Marib city is the Yemeni government’s last northern stronghold. It sits in an energy-producing region which has been the focus of fighting over the past year, during which Iran-aligned Houthi forces advanced towards the city. The fighting for Marib has dashed U.N.–led ceasefire efforts as both sides ramped up military operations. Aid agency Save the Children late on Thursday said 28 civilians had been killed or injured and that international law must be respected in Yemen’s seven-year conflict. “Civilians must be spared the horrors of ongoing fighting,” it said in a Twitter post. In the past few weeks the Houthis have launched a number of missile and drone attacks on Saudi Arabia, which leads a coalition backing the …