US stock markets faced significant declines as worries about rising tensions in the Middle East, particularly between the US and Iran, continue to impact investor sentiment. The S&P 500 and Nasdaq futures slipped, marking the end of a nine-day winning streak, while the Dow Jones industrial average fell more than 600 points. Oil prices climbed toward $100 a barrel as escalating hostilities and concerns over supply disruptions put additional pressure on markets. Analysts indicate that renewed conflict has dampened hopes for a diplomatic resolution and is contributing to volatility in both the equity and commodity markets.