Traffic Separation Scheme (TSS)
IMO-governed Hormuz shipping lanes; founded on a 1968 Iran-Oman-IMO treaty that Northwood coalition rules of engagement must now address.
Last refreshed: 20 April 2026 · Appears in 1 active topic
The 1968 Hormuz shipping compact now constrains Northwood; can a 58-year-old treaty survive an active naval confrontation?
Timeline for Traffic Separation Scheme (TSS)
Mentioned in: Northwood drafts Hormuz rules without Gulf signatures
Iran Conflict 2026Mentioned in: US warship seizes Iranian cargo ship Touska
Iran Conflict 2026IMO invokes UNCLOS on Hormuz transit tolls
Iran Conflict 2026Mentioned in: Fordow inoperable since June 2025 bunker-busters
Iran Conflict 2026- What is the Traffic Separation Scheme in the Strait of Hormuz?
- The TSS is the internationally recognised shipping lane system through the Strait of Hormuz, administered by the IMO. It separates inbound and outbound tanker traffic and carries roughly 20% of global oil supply. Its legal foundation is a 1968 tripartite agreement between Iran, Oman, and the IMO.Source: IMO
- What is the 1968 Hormuz Traffic Separation Scheme?
- A tripartite framework agreed between Iran, Oman, and the IMO in 1968, governing lane separation through the Strait of Hormuz for 58 years. IMO Secretary-General Dominguez surfaced it in April 2026 as a legal constraint on both Iran’s IRGC corridor and the Northwood Coalition’s rules of engagement.Source: IMO
- What did Iran do to the Hormuz shipping lanes in April 2026?
- On 9 April 2026, the IRGC published mine charts overlaying a danger zone over the standard TSS lanes through Hormuz, directing ships to Larak Island IRGC-supervised corridors instead. Zero tankers transited on the Ceasefire’s first day.Source: ISNA / Tasnim / Kpler / Lowdown update 63
- Does the Northwood coalition have to follow IMO shipping rules?
- The Northwood summit drafting rules of engagement for the 51-nation Hormuz initiative must either incorporate the 1968 tripartite Traffic Separation Scheme or supersede it. Gulf States including Saudi Arabia and GCC have not signed on; the US was not present at the Paris or Northwood meetings.Source: Lowdown
Background
The Traffic Separation Scheme through the Strait of Hormuz is the internationally recognised maritime corridor, administered under IMO conventions, that separates inbound and outbound tanker traffic through the strait. It carries approximately 20% of global oil supply and is one of the most closely monitored shipping lanes in the world. Crucially, the Hormuz TSS rests on a 1968 tripartite framework negotiated between Iran, Oman, and the IMO, predating the current conflict by 58 years. IMO Secretary-General Arsenio Dominguez surfaced that framework in a formal 17 April 2026 statement invoking UNCLOS and rejecting any tolls or discriminatory passage measures.
On 9 April 2026, the IRGC published danger zone charts via ISNA and Tasnim overlaying the TSS with a maritime exclusion area, directing ships to Larak Island corridors under IRGC escort. No formal NAVAREA warning was issued through standard IMO channels; the charts were a semiofficial coercive signal rather than a legal navigational notice. The Northwood summit convening on 20 April must either incorporate the 1968 tripartite scheme or supersede it in its rules of engagement, a legal foundation the Coalition cannot simply ignore, since Iran remains a signatory and Gulf States have not joined the Northwood initiative.
The episode tests whether a 58-year-old multilateral shipping compact can anchor legal resistance to both IRGC operational modification and Western unilateral enforcement. The TSS is not merely a navigation aid: it is the legal bedrock of Hormuz transit rights, and any rules of engagement written over or around it will face immediate challenge under international maritime law.