Oil prices extended gains for a fourth straight session as tensions between the United States and Iran continued to support crude markets, with no diplomatic breakthrough in sight. Brent crude rose to $91.14 a barrel and West Texas Intermediate was at $85.04, both close to recent highs, as traders priced in the risk that instability around the Strait of Hormuz, a key Middle East shipping chokepoint, could disrupt supply flows. Concerns have been reinforced by ongoing shipping constraints in the waterway and the involvement of U.S. forces in redirecting commercial vessels. At the same time, OPEC lowered its oil-demand growth forecast, adding a countervailing signal on consumption even as geopolitical risk kept upward pressure on benchmark prices. The market is now focused on any shift in the U.S.-Iran conflict, possible diplomatic efforts, OPEC production decisions and further changes in the Strait of Hormuz situation, all of which could influence near-term pricing.