What Happened
- South Korea entered active diplomatic consultations with Iran and other relevant nations to secure normalisation of shipping lanes through the Strait of Hormuz, which has been effectively closed since February 28, 2026.
- Seoul joined a seven-nation joint statement alongside European countries and Japan condemning Iranian attacks on commercial vessels and the de facto closure of the strait, reaffirming the principle of freedom of navigation.
- Iran is developing a selective vetting and registration system for ships transiting its territorial waters — allowing passage to ships from countries maintaining bilateral talks with Tehran, while blocking others.
- For South Korea, the strait is existential: over 20% of the world's oil trade passes through it, and South Korea imports nearly all of its crude oil from West Asian suppliers.
- Iran separately indicated readiness to allow Japan-bound vessels to transit, and data suggest tanker traffic through the strait is gradually resuming for selected flag states.
Static Topic Bridges
The Strait of Hormuz: Geography and Legal Status under UNCLOS
The Strait of Hormuz is a narrow waterway between the Musandam Peninsula of Oman and Iran, connecting the Persian Gulf to the Gulf of Oman and the Arabian Sea. At its narrowest point, it is approximately 39 kilometres wide. Crucially, the navigable shipping lanes — two lanes for inbound and two for outbound traffic — fall within Iranian and Omani territorial waters. This makes Iran's cooperation critical for safe transit. Under the United Nations Convention on the Law of the Sea (UNCLOS, 1982), Article 37 defines "straits used for international navigation," and Article 38 grants all ships the right of "transit passage" — a right that cannot be suspended even by the coastal state. However, Iran is not a signatory to UNCLOS, which complicates enforcement of these rights.
- Width at narrowest point: ~39 km
- Daily throughput: ~21 million barrels of oil (pre-closure)
- UNCLOS Articles 37–38: non-suspendable right of transit passage
- Iran is not a party to UNCLOS — disputes its application to the strait
- Navigable lanes pass through Iranian and Omani territorial waters
Connection to this news: Iran's "vetting system" for ship transit is legally contested under UNCLOS norms, and South Korea's bilateral diplomacy reflects the practical reality that enforcement of transit rights depends on Iran's consent given its non-UNCLOS status.
East Asian Energy Security and Fossil Fuel Import Dependence
South Korea, Japan, and China together account for a substantial share of global oil imports, almost entirely sourced from West Asia. South Korea imports nearly 90% of its energy and about 93% of its crude oil from abroad, with a majority coming through the Persian Gulf and the Strait of Hormuz. Any sustained closure of the strait therefore constitutes a first-order national security threat for Seoul. South Korea has no significant domestic oil production and maintains a Strategic Petroleum Reserve (SPR) as a buffer against supply disruptions. The strait closure has also disrupted the broader liquefied natural gas (LNG) supply chains critical to Japanese and Korean energy mixes.
- South Korea's crude oil import dependence: ~93% from abroad
- Japan's crude oil import dependence: ~99% from abroad
- ~30% of global LNG trade also transits the Strait of Hormuz
- South Korea and Japan are among the world's largest LNG importers
- Both nations have activated emergency energy protocols since February 28
Connection to this news: South Korea's active diplomatic engagement with Iran — going beyond the joint Western statement — reflects the asymmetry of energy vulnerability: East Asian nations face more acute consequences from the closure than European counterparts with greater supply diversification.
International Straits Diplomacy and the Precedent of Selective Access
Iran's emerging "vetting system" for Hormuz transit is unprecedented in modern maritime history. Historical precedents for strait access include the Montreux Convention (1936), which governs the Turkish Straits (Bosphorus and Dardanelles) and gives Turkey the right to restrict warship passage during wartime. The Hormuz situation differs: Iran controls access to a strait used for commercial energy trade rather than military passage, and is leveraging this control as a coercive tool in an active conflict. Countries including India, China, Pakistan, Malaysia, and Iraq are in bilateral negotiations with Tehran to secure passage rights.
- Montreux Convention (1936): governs Turkish Straits; Turkey may restrict warship passage in war
- No equivalent treaty exists for Hormuz — Iran's leverage is de facto, not de jure
- Countries in Hormuz access talks: India, China, Pakistan, Malaysia, Iraq, South Korea, Japan
- Iran's system: flag-state vetting, bilateral agreement required
- Even selective opening restores partial LNG and crude flows
Connection to this news: South Korea's bilateral approach mirrors that of India, China, and other Asian energy-dependent nations, signalling that effective Hormuz access is being managed through individual diplomatic deals rather than multilateral legal frameworks.
Key Facts & Data
- Strait of Hormuz daily oil flow (pre-closure): ~21 million barrels (~20% of global trade)
- ~30% of global LNG trade also passes through the strait
- South Korea's crude oil import exposure to Persian Gulf: majority of 93% seaborne imports
- Nations in bilateral Hormuz transit talks with Iran: India, China, Pakistan, Malaysia, Iraq, South Korea, Japan
- Joint statement signatories against Iranian vessel attacks: UK, France, Germany, Italy, Netherlands, Japan, Canada, South Korea
- Iran's approach: selective blockade with registration/vetting system
- UNCLOS Articles 37–38: right of transit passage (Iran is not a signatory)