The Iranian-backed Houthi rebel group in Yemen launched a wave of attacks on Saudi Arabia on Tuesday, wounding more than 70 people and igniting fires at oil facilities and utilities in the kingdom, authorities said.The attack was a major escalation in renewed fighting between an important US ally and the Iranian proxy group. It also threatened to further destabilise a region rocked by nearly three years of wars and deliver a new blow to the global economy.Weeks of clashes have added pressure to limited global oil supplies as the Houthis target a shipping route Saudi Arabia has used to transport oil to world markets while the Strait of Hormuz is throttled due to the US-Iran war.Tuesday’s attacks hit Saudi oil facilities connected to the alternative route, the Bab el-Mandeb, a strategic waterway off the southern tip of the Arabian Peninsula that connects the Red Sea to the Gulf of Aden.Yemeni government forces and National Resistance Forces fire at Houthi fighters on the Kadha front, west of the city of Taiz, on Tuesday. Photo: Yemen National Resistance Forces / AFPThe conflict between Saudi Arabia, one of America’s closest Mideast allies, and the Houthis, a Shiite militant group armed and trained by Iran, goes back years.