Strait of Hormuz Selective Transit Regime Pushes Oil Past $108 as Iran Tightens Grip

Iran's Islamic Revolutionary Guard Corps has escalated its control over the Strait of Hormuz in early April 2026, implementing what analysts are calling a selective transit regime that allows Iranian-allied vessels to pass while subjecting tankers linked to US coalition partners to boarding, inspection, and in some cases forced diversion.

The regime marks a shift from the near-total closure that drove oil above $126 in March to a more calibrated chokepoint strategy. By permitting some traffic while blocking others, Tehran maintains leverage without triggering the full-scale military response that a complete closure would invite.

Brent crude closed at $108.42 on April 4, reflecting the market's recalibration. While prices have retreated from March peaks, the selective regime introduces a new kind of uncertainty: operators cannot predict whether any individual transit will be permitted. This unpredictability has proven more damaging to insurance markets than a binary open-or-closed scenario.

War-risk premiums for Hormuz transits now range from 2.5 to 5 percent of hull value, according to Lloyd's market sources. For a VLCC valued at $120 million, that translates to $3-6 million per transit on top of standard P&I coverage. Several International Group clubs have issued circulars advising members that coverage remains subject to 48-hour cancellation clauses for vessels entering the Persian Gulf.

The Japan-brokered safe passage corridor announced in late March has shown mixed results. Japanese-flagged and Japanese-chartered vessels have transited without incident, but vessels chartered by South Korean and European operators have reported IRGC patrol boat approaches and radio challenges. Tokyo's Foreign Ministry confirmed that 14 Japanese-linked transits have completed successfully since March 28, but declined to comment on vessels of other nationalities.

For the global tanker market, the selective regime is reshaping trade flows. VLCCs that would normally load at Ras Tanura or Kharg Island are instead positioning for longer West African and US Gulf routes. Ton-mile demand has increased an estimated 12 percent as refiners source crude from non-Hormuz producers. This structural shift benefits tanker owners with modern, fuel-efficient tonnage while squeezing older vessels with higher operating costs.

The geopolitical calculus is delicate. CENTCOM continues strike operations against Iranian coastal defense installations, having degraded an estimated 40 percent of Iran's anti-ship missile capacity along the southern coastline. But military degradation of launch sites has not translated into freedom of navigation for commercial shipping. The insurance market, not the Iranian navy, remains the binding constraint.

Analysts at the Middle East Institute assess that the selective regime could persist for weeks or months, creating a new normal where Hormuz functions at 30-40 percent of pre-crisis capacity. This is enough to prevent a global supply crisis but insufficient to bring prices below $100 without additional diplomatic progress.

The next inflection point is the expiration of Treasury Secretary Bessent's 30-day Iranian oil sanctions waiver on April 21. If the waiver lapses without renewal, the 140 million barrels of Iranian crude currently flowing under the exemption will be re-sanctioned, potentially sending prices back above $115.