US and Iranian tensions: Charterparty implications in Marine Insurance P&I Club News 26/02/2026 Despite ongoing diplomatic efforts, tensions between the United States and Iran continue to escalate, primarily due to Iran’s nuclear programme. The US has responded to these developments by significantly increasing its military presence in the Middle East, reinforcing regional forces, deploying major naval assets, including the USS Abraham Lincoln carrier strike group, and ramping up aircraft patrols, surveillance, and readiness exercises. On 17 February, Iranian state media reported a partial closure of the Strait of Hormuz; however, no complete closure has occurred to date. Iran has seized commercial vessels and oil tankers in the region, often citing alleged smuggling offences. On 9 February, the US Department of Transportation’s Maritime Administration (MARAD) issued an advisory urging US-flagged commercial vessels to avoid Iranian territorial waters when transiting the Strait and to refuse permission for Iranian forces to board if requested. Vessels are also advised to keep AIS transponders operational unless otherwise directed by the US Navy. Reports have emerged of Iranian authorities attempting to force commercial vessels into their territorial waters, coinciding with a US Navy fighter jet’s interception of an Iranian drone near the USS Abraham Lincoln. Since mid-2025, there has been a notable increase in incidents of GPS and AIS jamming and spoofing around the Hormuz Strait, often attributed to Iranian electronic interference. Jamming involves overwhelming a GPS receiver with powerful signals, impeding its functionality, while spoofing supplies false data to the receiver, misleading it about position and time. Such interference poses significant safety risks: a vessel misled by spoofed GPS data may stray off course, risking collisions or groundings, and could be unknowingly lured into national waters where the risk of seizure is much higher. The Strait of Hormuz and its significance The Strait of Hormuz is a critical shipping channel, serving as the only sea passage from the Persian Gulf to the open ocean. Approximately 35% of the world’s seaborne oil passes through the Strait, which narrows to just 22 nautical miles (32 km) at its tightest point. The international legal framework governing the Strait is complex and contested. Under the UN Law of the Sea Convention 1982 (UNCLOS), flagged vessels have the right of innocent passage through coastal state territorial waters. The Strait qualifies as a strait used for international navigation within UNCLOS, granting vessels the broader right of transit passage.[i] However, Iran has not ratified UNCLOS and disputes the existence of transit passage rights under customary international law. As a result, disputes regarding navigational freedoms in the Strait are expected. At present, the Hormuz Strait remains open, but concerns about regional stability continue to rise. The possibility of a blockade or closure remains, as does the targeting or seizure of vessels with US or allied connections. There is also a risk of vessels being unintentionally struck by sea mines, drones, or stray missiles, and confiscation remains a serious threat. English law charterparty implications This article explores key English law charterparty implications arising from hostilities in the region, including potential closure of the Strait and risks posed by AIS and GPS jamming and spoofing. War risks clauses Many ch