Signal

Maritime: Chaos in the Strait of Hormuz

Signal of the Twelve-Day War, June 2025

GPS jamming and spoofing around the Strait of Hormuz surged to roughly 1,000 vessels a day, scrambling ship positions so badly that supertankers appeared to sail over land, through airports, and across a nuclear plant, and helping cause a VLCC collision on 17 June. Transits through the Strait fell about 20-25%, tanker freight and war-risk insurance jumped, and Iran's parliament backed closing the Strait after the US strikes, but it never actually closed before the ceasefire.

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The question
What happened to the world's most important oil chokepoint, and did Iran actually close it?
About 1,000 ships a day hit by GPS interference
Maritime intelligence firm Windward found roughly 970-1,000 vessels a day experiencing GPS jamming or spoofing in the Gulf and Strait in mid-June, concentrated near Bandar Abbas.
Ships shown sailing over land
Spoofing put impossible positions on screens: supertankers circling over dry land, cargo ships crossing airports, vessels drifting through a nuclear power plant. Prof. Todd Humphreys judged it 'almost certainly' Iranian.
A VLCC collision linked to the jamming
On 17 June the crude supertanker Front Eagle collided with the tanker Adalynn near the Strait after sustained GPS/AIS jamming falsely placed Front Eagle inside Iran; there was a deck fire but no casualties.
Transits fell about 20-25%
Daily Strait transits dropped from 147 vessels on 9 June to 111 on 15 June as owners waited outside; tanker CEOs described roughly 20% less passage.
War-risk insurance roughly doubled
Hull war-risk premiums for the Gulf roughly doubled to 0.2% of vessel value, and VLCC Gulf-to-China freight rates jumped 24% in a single day on 13 June.

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