The narrow waters of the Strait of Hormuz have long been a fulcrum of global energy security, and the man who holds the ultimate authority over Iran’s ability to disrupt that passage is Ayatollah Ali Khamenei, the Islamic Republic’s Supreme Leader since June 4, 1989. At 85 years old as of 2025, Khamenei remains the decisive voice on Iran’s nuclear program, foreign policy, and military posture.
His endorsement in 2018 of the Islamic Revolutionary Guard Corps’s threats to block the strait in response to U.S. sanctions underscored a long-standing doctrine of deterrence through disruption, one rooted in Iran’s geographic position and its reliance on asymmetric economic weapons. For the United States, the practical consequence is stark: any closure of that waterway would send oil prices spiking, directly affecting American drivers and businesses, as the strait carries the bulk of crude exports from Saudi Arabia, Iraq, the United Arab Emirates, Kuwait, Bahrain, Qatar, and Iran itself.
The Machinery of Control
Khamenei’s grip on power is not merely symbolic; it reaches every branch of the Iranian state. He heads the Assembly of Experts, the body theoretically charged with selecting his successor, and controls the Guardian Council, which vets candidates for all elected offices. This structural advantage allows him to act as a gatekeeper, determining which players may enter the political arena.
No major decision, from nuclear negotiations to domestic crackdowns, moves forward without his sign-off. Born on July 17, 1939, in Mashhad, Iran, Khamenei succeeded Ruhollah Khomeini and has since consolidated authority over the Islamic Revolutionary Guard Corps and the regular military.
The United States imposed sanctions on him directly in 2019, freezing any assets he holds under American jurisdiction and barring U.S. persons from dealing with him. That financial squeeze, however, has not visibly loosened his domestic authority. His age and the opacity of Iran’s succession planning make his health a continued focus, though no official update has altered his role as the final arbiter of state policy.
Strategic Leverage and Opposition to U.S. Influence
Khamenei has consistently opposed U.S. influence in the Middle East, a stance that shapes Iran’s support for proxy forces including Hezbollah in Lebanon and Houthi rebels in Yemen. The Strait of Hormuz remains his most direct economic weapon.
Historically, Iran has viewed control of the strait as a national security interest, dating back to the Iran-Iraq War in the 1980s, when Tehran targeted shipping there to counter Iraq’s blockade and international support for Baghdad. The threat to close the strait became a recurring leverage tactic, formally endorsed by the Supreme Leader in 2018 when he backed IRGC threats to block the waterway in response to U.S. sanctions. This doctrine of deterrence through disruption relies on Iran’s geographic position and its asymmetric military options.
The strait’s strategic importance has grown since the mid-20th century, when Western companies developed large-scale oil fields in the Persian Gulf, making producers there central to world energy markets. By the 1970s, most Gulf oil traded by sea passed through the strait, a role that continues today because of the concentration of major producers along its shores.
Any interruption, whether through conflict, sabotage, or deliberate action, can ripple through global energy markets, affecting fuel prices and supply chains far beyond the region.
Uncertain Succession and What to Watch
Khamenei’s health, a persistent subject of speculation given his age, puts a spotlight on Iran’s opaque succession process. The Assembly of Experts, which he heads, would choose his successor. Because Khamenei controls the Guardian Council, the vetting body for candidates to the Assembly itself, the process is structured to make it unlikely that a leader deviating sharply from his anti-Western posture would emerge.
For any U.S. administration seeking to curb Tehran’s nuclear ambitions or regional meddling, the Supreme Leader remains the fixed point in Iran’s political calculus — and the central obstacle. As energy traders, policymakers, and consumers watch the Strait of Hormuz, Khamenei’s capacity and willingness to wield that leverage will continue to shape global markets and international relations, making his role a persistent flashpoint in the broader contest between Washington and Tehran.
