The operation marks the most direct American military intervention inside Iran in decades and has reignited fears of a rapidly widening conflict that could draw in proxy forces, endanger U.S. troops, and disrupt global energy markets.

After nearly two years of stark divisions over the war in Gaza and support for Israel, Democrats seemed at odds over policy toward Iran as progressives demanded unified opposition before President Donald Trump announced U.S. strikes against Tehran’s nuclear program. Party leaders were treading more cautiously.