At the narrow throat of the Persian Gulf, where a third of the world's oil passes each day, Iran has declared an exclusion zone near the Strait of Hormuz — a move less about closing a waterway than about reminding the world who stands on its northern shore. The announcement, deliberately vague in its boundaries and enforcement, follows a long pattern of Iranian maritime assertion: claiming influence without quite crossing the line that would demand a military answer. In a region where geography is leverage, Tehran has once again placed its hand on one of civilization's most consequential valve