A neutral state interned an Iranian warship in March. Almost no one covered it.

Sri Lanka took custody of the IRIS Bushehr and its 208 crew in March 2026, invoking a 1907 neutrality convention that had lain dormant for decades. Almost no one covered it.

Sri Lanka took custody of the IRIS Bushehr and its 208 crew in March 2026 — a rare invocation of a 1907 neutrality convention that has lain dormant for decades.

On March 5, 2026 — days after the joint U.S.-Israeli Operation Epic Fury strikes that opened the Iran-Israel war — Sri Lanka took control of the Iranian Islamic Republic Navy replenishment ship IRIS Bushehr off the southern coast. The Bushehr had requested to enter port on March 4, after the U.S. Navy submarine USS Charlotte sank the Iranian frigate IRIS Dena with torpedoes south of Sri Lanka the same day. Both ships had been returning from India's Milan 2026 naval exercise and International Fleet Review at Visakhapatnam. Al Jazeera reported 84 Iranian sailors killed in the Dena sinking, and Sri Lanka repatriated the recovered remains via Mattala airport; Sri Lankan accounts put the recovered dead at 84 and rescued 32 survivors.[1][2][3]

The Sri Lankan government accepted the request. Under the customary law of naval warfare, a neutral state that grants port to a belligerent warship must, after a brief permitted stay of typically 24 hours, either compel the warship to depart or intern it for the duration of the conflict. The Sri Lankan authorities chose internment.[4][5][6]

The 208 crew of the Bushehr were taken into Sri Lankan custody and transferred to the Welisara naval base, with consular access through the Iranian embassy in Colombo. The ship itself was escorted to the deepwater harbour at Trincomalee on Sri Lanka's east coast, where it remains as of May 2026 under Sri Lankan Navy guard.[5][7] The Hague-XIII internment doctrine the case invoked has not been formally applied to a major warship in decades. The reasons Sri Lanka chose internment over the obvious alternatives are the more interesting part of the story.

The legal frame: what internment actually means

The relevant body of law is the 1907 Hague Convention XIII concerning the Rights and Duties of Neutral Powers in Naval War, together with the customary international law of neutrality that has developed around it in the decades since World War II. Hague XIII provides that a neutral state may permit a belligerent warship to enter its ports for a maximum of 24 hours, except in cases of damage or stress of weather, in which case the stay may be extended only as long as necessary to make the vessel seaworthy. After the permitted stay, the neutral state must compel the warship to depart. If the warship cannot or will not depart, the neutral state must *intern* it: the vessel is taken into custody, the crew is disarmed and confined ashore for the duration of the conflict, and the vessel is held until hostilities end.[4][5]

The doctrine is straightforward in theory and almost never applied in practice. The reason is that, since the late 19th century, the cost-benefit of internment to a neutral state has heavily favoured expulsion. Interning a warship requires the neutral state to: physically secure the vessel against external attack or rescue attempts by the belligerent's allies; provide food, medical care, and consular access to the interned crew, often for years; bear the diplomatic friction of being publicly understood as having "sided" against the belligerent whose ship was interned; and accept the post-war negotiation of how the vessel is returned, often involving claims for damage or upkeep.

The doctrine's best-known historical applications belong to the early 20th century: the internment of the Russian cruiser *Aurora* and other ships of the Asiatic Squadron at Manila by the United States in 1905 during the Russo-Japanese War, and the German pocket battleship *Admiral Graf Spee*, whose captain chose to scuttle her off Montevideo in 1939 rather than face internment by Uruguay. Internment of major warships effectively ceased to feature in great-power conflict after 1945, in part because the triggering cases — a stranded belligerent warship and a willing neutral port — stopped arising. The Sri Lankan decision in March 2026 is best understood as a contemporary application of a long-dormant body of law rather than a routine diplomatic event.

That this happened received almost no coverage in the Western press. The Bushehr case was reported as a single-news-cycle item by USNI News, NPR, Al Jazeera, and Iran International; the legal dimension was largely not picked up by the major U.S. or European newspapers, which were absorbed in the strikes on Iran and the Strait of Hormuz closure.[1][2][3][7]

Why Sri Lanka chose internment

Sri Lanka's choice was not obviously the path of least diplomatic resistance. Three alternatives were available.

First, the Sri Lankan government could have refused entry, citing the 24-hour limit, and required the Bushehr to depart. This would have placed the ship in immediate operational jeopardy — without a friendly port within steaming range and with U.S. attack submarines confirmed to be in the area, the Bushehr would in all likelihood have been sunk within a few days, with the consequent loss of 208 crew. The diplomatic and humanitarian implications for Sri Lanka of refusing refuge to a non-combatant supply vessel under those conditions would have been substantial.

Second, Sri Lanka could have permitted the Bushehr to enter, resupply, and depart within the 24-hour limit, implicitly accepting that the ship would be sunk shortly after. Both the Sri Lankan press and the Iranian government would have presented this as effective complicity in the destruction of an unarmed vessel. That would have damaged Sri Lankan-Iranian relations, which carry real economic content for Colombo, without offering any compensating diplomatic value.

Third, Sri Lanka could have done what it did: intern the vessel. The internment preserved Sri Lankan neutrality in the eyes of customary international law, did not require Sri Lanka to take a side in the substantive dispute between Iran and the U.S.-Israeli coalition, prevented the loss of 208 Iranian sailors, and placed Sri Lanka in a politically useful position as a neutral custodian rather than as a passive bystander. The Iranian government's public reaction was, on the available record, muted; Tehran did not formally protest the internment, did not recall its ambassador, and accepted the consular-access arrangement.[5][7]

The deeper reason Sri Lanka was positioned to make this choice is the country's non-aligned diplomatic tradition. Sri Lanka has been a member of the Non-Aligned Movement since the movement's founding in 1961 and has maintained, through governments of varying ideological orientation, a foreign policy that avoids formal alignment with major-power blocs. The country's ports have served, in different periods, as fuelling stops for Soviet submarines, U.S. carrier groups, Indian fleet exercises, and Chinese Belt-and-Road maritime infrastructure. The diplomatic infrastructure for managing a complex Hague-XIII internment — neutral consular protocols, naval-base secure facilities, multilingual diplomatic staff — was, by accident of geography and history, already in place.

A second factor was the regional context. India faced a parallel case of its own: a separate Iranian naval vessel, the IRIS Lavan, sought refuge at an Indian port and was interned by India on March 4. India's own complex relationship with Iran — Chabahar port investment, oil purchases under sanctions exemptions, a large Indian labour presence in the Iranian Gulf — meant New Delhi and Colombo confronted the same legal question within a day of each other, and both reached the same answer.[9] That a larger neighbour took the identical course made internment less diplomatically exposed for Sri Lanka.

What the case demonstrates

Three propositions about the contemporary international order are illustrated by the Bushehr case.

The first is that Hague-XIII internment doctrine remains legally available and practically operational. The customary international law of naval warfare has not been displaced by U.N. Charter-era norms; in a confrontation between a belligerent's stranded warship and a neutral's port, the eighty-year-old precedent works exactly as it was designed to work. The fact that the doctrine has not been invoked in eight decades reflects the absence of triggering cases, not the absence of legal validity.

The second is that small neutral states retain genuine diplomatic agency in even the most consequential great-power confrontations. Sri Lanka, a country of 22 million people with limited military capacity and substantial economic vulnerability, made a unilateral decision that materially constrained both U.S. and Iranian options without consulting either Washington or Tehran in advance. The U.S. did not pressure Sri Lanka to refuse internment; Iran did not pressure Sri Lanka to refuse to intern. The Sri Lankan government acted in what it judged to be its own diplomatic interest and was permitted to do so. This is a useful corrective to the framing of contemporary international relations as one in which only the major powers have meaningful agency.

The third is that the war has produced legal and diplomatic events that have little recent precedent. The Iran-Israel-U.S. war is, at the level of its main events, a recognizable regional conflict: strikes, retaliations, oil-market disruptions, alliance-management problems. Beneath that, it has generated a set of secondary events that test rarely-used machinery of the international system. The Bushehr internment is one. The Strait of Hormuz closure and the U.K. response to the strikes on RAF Akrotiri (both covered separately on this site) are others, each adding to the inventory of what the post-2026 system has shown itself capable of.

That a small Indian Ocean state interned a major naval power's warship under a 1907 convention, and that this was barely covered, tells us something about Sri Lanka's diplomatic positioning and about the limits of Western press attention to events outside the great-power narrative. The Bushehr remains in Trincomalee. The 208 crew remain in Sri Lankan custody. The case will likely be cited in the law-of-naval-warfare literature as a contemporary application of Hague XIII. The people involved will spend the rest of the war in a Sri Lankan facility waiting for it to end.

Open in the interactive site →