Talk of Iran closing the Strait of Hormuz is back. You’ve heard this before but this time feels different. Here’s a fast, clear thread: What the Strait is Why it matters Who controls what How Iran could disrupt it What happens if it spirals 1/24.

1/The Strait of Hormuz is the world’s most critical maritime chokepoint. Connects the Persian Gulf to open waters Just 21 miles wide at its narrowest A third of global seaborne oil flows through it Used by over 30% of LNG exports globally

2/An average of 17 million barrels of oil per day pass through Hormuz. That’s more than: The U.S. or Russia produces daily Half of OPEC’s total exports 20% of total global oil consumption Any disruption = instant price shock.

3/Control is divided: North of the Strait: Iran South of the Strait: UAE and Oman Main shipping lanes: International waters but just 2–3 miles wide in each direction

4/Iran also controls 3 key islands in the Strait: Abu Musa Greater Tunb Lesser Tunb All are militarized with missile launchers and IRGC Navy presence. These are launch points for fast attack boats, mines, or missile threats. (UAE have claims over this islands too)

5/To reduce collision risk, ships follow a Traffic Separation Scheme (TSS) through the Strait. Inbound ships: 2-mile lane Outbound ships: 2-mile lane Separated by a 2-mile-wide buffer (median) All within international waters but very narrow margins

6/Iran’s threats aren’t new but always serious. They've long said that if Iranian oil can’t be exported, no one’s oil will. Each time, markets pay attention. (AND ME TOO).

7/Iran can’t simply close the Strait But it can disrupt it enough to freeze commercial traffic or spike insurance costs. How? Lay naval mines Swarm tankers with fast boats Launch anti-ship missiles Launch drones from the islands

8/These tactics will hurt. Even without full closure. Just look at the Houthis with basic drones and missiles, they’ve disrupted Red Sea shipping for months. Hormuz is right in Iran’s backyard, not 1,500km away like Israel. Much easier.

9/U.S. and allied navies patrol the Strait U.S. 5th Fleet is based in Bahrain Often joined by UK, France, regional forces Protecting freedom of navigation is the mission but in such narrow waters, incidents can happen fast

10/We’ve seen this before. 1980s Tanker War during the Iran–Iraq war 2019: Mysterious attacks on tankers near Fujairah 2023: IRGC naval harassment and drone flights These events drove oil prices up even without full closures.

11/Some countries built pipelines to bypass Hormuz: UAE’s Habshan–Fujairah pipeline Saudi East-West pipeline to Red Sea Iraq to Turkey via Ceyhan (but it’s capacity-limited) Combined, they handle <10% of Gulf exports.

12/So if Hormuz stops even briefly the world feels it. Effects within 24 hours: Brent and WTI oil spike LNG markets go volatile Tanker insurance premiums multiply Refiners in Asia start bidding for emergency cargo

13/But remember this: >75% of oil exports through Hormuz go to Asia China imports the most by volume But Japan, South Korea, and India are more dependent Hormuz accounts for the majority of their crude intake

14/That’s key: China has some options, but others don’t. Japan and South Korea, in particular, lack: Strategic pipelines Sufficient reserves Political leeway to shift rapidly Their economies are tightly linked to stable Hormuz flows.

15/It’s not just crude. Liquefied natural gas (LNG) from Qatar Jet fuel, diesel, naphtha, and petrochemicals Electronics and food cargoes in containers The Strait moves a broad mix of critical goods, not just energy.

16/Iran’s naval doctrine leans on: Fast attack craft Mini-subs Missile corvettes Land-based cruise/ballistic anti-ship missiles Loitering munitions (drones) Coastal artillery near Bandar Abbas and Qeshm Island

17/Even attempting to close the Strait would backfire on Iran. It would: Halt its own exports (oil, condensate, LPG) Trigger U.S./GCC military response It’s a last-resort, near-suicidal option but one they keep on the table.

18/The U.S. Navy would intervene within hours. Capabilities include: Mine-clearing ships Carrier-based air patrols Long-range strike platforms. Still, clearing a mined strait takes days to weeks.

19/Strategic petroleum reserves (SPR) in OECD countries offer only a short-term cushion. Japan: 145 days of imports South Korea: 90+ days U.S.: Drawdown possible but not instant India: Only ~25–30 days in strategic tanks Not enough if flow stops for long.

20/Maritime insurers react quickly even without a full blockade In 2019, war risk premiums for tankers in the Gulf rose 10x in a month Some vessels rerouted entirely Smaller operators simply paused sailings This has the same effect as an actual blockade.

21/Military simulations have long tested scenarios where Iran tries to shut the Strait. Some showed major U.S. losses and weeks of disruption. Others said reopening could take just days. Either way those were old models. My view? Reality would look very different today.

22/Iran has the tools to disrupt the Strait but closing it fully would be a suicidal move. It would trigger massive escalation, risk total isolation, and hurt its own friends, like China. But if Iran feels cornered or collapsing, it could see this as a last resort.

23/Anyway lots more to say, but here’s the quick version. The Strait of Hormuz really matters. Yes, Iran can disrupt it. But in my view, that’s a last-resort move something they’d reach for only if the regime is collapsing. For now, it’s more about pressure than action.

And remember China isn’t immune to a Strait shutdown. It’s the largest importer of Gulf oil by volume. Disruption here would hit it hard, especially early on. Yes, it’s in a stronger position than others. But it bleeds too.

Many in the comments says Iran would only close the Strait of Hormuz to "non-friendly" countries. That misses the point once it turns into a war zone, no one’s safe. It’s not the Red Sea. It’s the Strait of Hormuz one of the world’s narrowest, busiest chokepoints. Friendly or not, the danger affects everyone.