Oil prices rose sharply on Friday, gaining more than 2% and settling at their highest levels since the end of April as concerns about a potential escalation in the war with Iran increased ahead of the November 3 U.S. midterm elections. Brent crude futures for December delivery settled up $2.76, or 2.4%, at $117.64 a barrel, while the more active January contract gained $2.63 to $113.43. U.S. West Texas Intermediate (WTI) crude futures rose $2.12, or 2.08%, to $104.12 a barrel. For October, Brent gained 13.6%, while WTI rose 15.2%.

Supply concerns intensified after a tanker was struck by explosive devices attached to its hull by a small boat while traveling through the Strait of Hormuz. The attack marked the first known successful use of limpet mines against a vessel in the waterway since the conflict with Iran began in February. Meanwhile, Yemen’s Iran-aligned Houthis claimed attacks on several Saudi energy facilities, including the Ras Tanura and Rabigh refineries and an Aramco production facility in Abqaiq. A Saudi-led coalition also reported intercepting a Houthi cruise missile. At the same time, Qatari mediators returned to Tehran to continue efforts toward a potential agreement between the United States and Iran, although negotiations remain uncertain. Concerns about further military escalation following the U.S. midterm elections continued to support prices.

Saudi Arabia’s crude exports increased in October compared with September, according to two of three ship-tracking companies, despite continued attacks on shipping and threats to energy infrastructure. In the United States, the oil rig count increased by two, while EIA data showed that crude oil production rose in August as demand for crude oil and petroleum products declined. Supply concerns also emerged in Libya after an armed group shut a valve on the main Hamada crude pipeline, halting approximately 15,000 barrels per day of flows to the Zawiya refinery.