Oil prices surged after President Trump declared in a White House address that the war on Iran was 'nearing completion' while promising intensified military action over the next two to three weeks. Brent crude jumped nearly 5 percent to $106 a barrel, while West Texas Intermediate rose 4 percent to $104. The Strait of Hormuz, a critical oil shipping route carrying one-fifth of global supply, has seen shipping traffic effectively halted since the conflict began.

Asian markets reacted sharply to the escalating tensions, with Japan's Nikkei 225 falling 1.5 percent and South Korean stocks dropping 2.6 percent. U.S. stock futures pointed to a 1 percent decline for the S&P 500 when trading resumes Thursday. The market volatility reversed Wednesday's gains, when the S&P 500 had risen 0.7 percent.

U.S. gasoline prices climbed to a national average of $4.06 per gallon, up 36 percent since the war began, according to AAA. Diesel prices rose even faster, reaching $5.49 per gallon, a 46 percent increase. Energy analysts note that fuel prices typically lag crude oil movements by several days, suggesting further increases may be on the horizon.