In the ancient contest between rival powers, proxy forces have long carried the weight of larger ambitions — and on Saturday, the Houthis of Yemen brought that old truth into sharp relief, launching a coordinated wave of missiles and drones against Riyadh and Saudi Arabia's oil infrastructure. Backed by Iran, the group struck at the twin pillars of Saudi power: its capital and its energy wealth. The attack is less a singular event than a signal — that the regional struggle between Tehran and Riyadh has entered a more dangerous register, and that the world's energy markets may yet feel the trem