Iran-backed Houthi militia forces based in Yemen attacked four Saudi cities and energy facilities on Tuesday, raising concerns that the conflict could widen as oil prices approach $100 a barrel. Saudi Arabia, the world’s third-largest crude oil producer, halted operations at some energy facilities, although the effect on production remains unclear. Continued attacks could remove crude or refined products from global markets and further disrupt Gulf energy supplies. Traffic through the Strait of Hormuz (a vital Gulf oil shipping route) also slowed on Monday after Iran threatened retaliation for further U.S. attacks, while the Houthis continued targeting shipping around the Red Sea. Higher oil prices could intensify inflation pressure as the Federal Reserve considers whether to raise interest rates in September following a stronger-than-expected August jobs report.