Crude oil prices surged on Monday as the initial effects of U.S. and Israeli strikes against Iran began to emerge. Shipping traffic through the Strait of Hormuz nearly halted, and production at a major Saudi refinery was disrupted, creating turmoil in energy markets. Brent crude futures closed up approximately 6.7%, settling near $78 per barrel, marking the largest single-day gain since June 2025. Oil prices continued to climb after market close, as Iranian state media reported a spokesperson for the Islamic Revolutionary Guard Corps stating that Iran would not allow oil to flow out of the region. Diesel futures, a key indicator for the global economy, settled near their highest level in almost three years. As airstrikes entered their third day, the U.S. conveyed conflicting messages regarding the potential duration of the conflict with Iran. A prolonged war is expected to further disrupt energy markets and block critical shipping lanes. U.S. President Trump stated that operations are anticipated to last four to five weeks but that the U.S. is prepared for a longer engagement. U.S. Defense Secretary Hagel denied that this would be an "endless" war. Meanwhile, Iran's security chief ruled out the possibility of negotiations. Helima Croft, head of commodity market strategy at RBC Capital LLC, noted in a report that if the conflict persists, oil prices could reach levels above $100 per barrel. J.P. Morgan estimated that if disruptions in the Strait of Hormuz continue for 25 days, oil-producing nations would exhaust their storage capacity, forcing production cuts. In Europe, liquefied natural gas prices rose sharply on Monday after Qatar suspended production at the world's largest LNG export facility following an Iranian drone attack. Analysts at Citigroup, including Max Layton, stated in a pre-market report that under their baseline scenario, Brent crude would trade in a range of $80 to $90 per barrel for at least the next week. Morgan Stanley raised its second-quarter Brent price forecast from $62.50 to $80 per barrel. May Brent crude futures increased by 6.7%, settling at $77.74 per barrel, after briefly reaching $82.37. April WTI crude rose 6.3%, closing at $71.23 per barrel.