International crude futures extended sharp gains on August 17 after a memorandum of understanding between the United States and Iran expired, reviving concerns that tensions could disrupt flows through the Strait of Hormuz, a critical oil shipping chokepoint. WTI (U.S. crude benchmark) for October delivery settled at $83.65 a barrel, up $2.13, or 2.61%, while Brent rose $2.35, or about 2.7%, to $90.87 in London. President Donald Trump said he would not extend the expired MOU, and an Iranian Foreign Ministry spokesman signaled to Tasnim News Agency that Tehran would also reject an extension of negotiations. Reports that Iranian officials were prepared to resort to military strikes to break a blockade of the Strait of Hormuz, along with the U.S. Treasury Secretary's policy of tighter sanctions and a naval blockade, heightened supply concerns. Additional support came from reports that Yemen's Iran-backed Houthi rebels targeted Saudi Arabia's Jizan refinery and from the International Energy Agency's warning of a deepening global supply deficit. The rally in oil weighed on broader markets, with the Dow Jones Industrial Average and Nasdaq Composite both falling as higher crude prices and stronger U.S. data pushed long-term yields higher. The U.S. Strategic Petroleum Reserve (emergency government oil stockpile) fell by about 5.3 million barrels to 293.4 million barrels, its lowest since December 1982, reinforcing concerns that prices could face further upward pressure if supply risks worsen.