In the ancient calculus of oil and conflict, markets paused Thursday to weigh whether a sharp U.S.-Iran military exchange near the Strait of Hormuz marked a turning point or merely an intermission. Brent crude and WTI both retreated modestly as traders found more meaning in the silence following the strikes than in the strikes themselves. The world's most critical oil chokepoint — through which a third of all seaborne crude passes — had been reduced to a trickle of four vessels where thirteen normally sail, and the question hanging over every price was whether that quiet would hold.