ADEN/DUBAI — Saudi Arabia has shut down its East-West pipeline after the vital oil conduit came under aerial attack in the widening Middle East war, threatening to send energy prices even higher. The world’s largest crude oil exporter temporarily closed the pipeline after a drone attack that both Baghdad and Riyadh said had originated in Iraq, where Iranian-backed militias operate. Iraq dismissed a military commander on Saturday in response to the attack. The 1,200-km (745-mile) pipeline running across the Arabian Peninsula had helped Saudi Arabia to bypass a shipping logjam in the Strait of Hormuz, where tanker traffic has slowed to a trickle due to the six-month war between the U.S. and Iran. The Saudi Energy Ministry said it had shut the pipeline as a precaution. The line has been moving 4 million to 5 million barrels per day in recent months, amounting to 4% to 5% of global supply, according to ship tracking companies and analysts. It was not immediately clear who was responsible for the strikes. Satellite images showed black smoke rising from an area of the pipeline south of Med