Yves right here. Except for the truth that the tanker monitoring is a technically fascinating, notice the remark on the prime. The authors imagine that the amount of discounted sanction-busting shipments is so giant that ending the sanctions would increase, not decrease, oil costs. That is opposite to the widely-presented views of the Trump-sympathetic YouTubers, and one suspects, the Trump Administration too.
By Jesús Fernández-Villaverde, Yiliang Li, Le Xu, and Francesco Zanetti. Initially revealed at VoxEU
Regardless of formal restrictions, untracked oil continues to achieve world markets, calling into query the true effectiveness of oil sanctions. This column presents a novel ship clustering mannequin to detect ‘darkish transport’ – the place tankers disable their location indicators to evade detection – linked to sanctioned oil transport. Following Western sanctions on Russia in 2022, formally recorded Russian oil exports declined, however shipments through darkish vessels greater than doubled. A big share in the end reaches non-sanctioning international locations. The elevated availability of discounted, dark-shipped oil helps preserve world costs down.
In recent times, sanctions have turn out to be a steadily used device for Western authorities to curb oil exports from focused economies, aiming to scale back the latter’s export revenues by proscribing entry to main markets. Nonetheless, the broader penalties of such measures stay unsure – significantly given mounting proof that some tankers ‘go darkish’ by disabling their location indicators to evade detection and break the sanctions. Moreover, the consequences on the worldwide provide chain are sometimes neglected, elevating additional questions concerning the true influence of those restrictions.
The unauthorised follow often known as ‘darkish transport’ has gained growing consideration within the context of sanctions on international locations reminiscent of Iran, Syria, Venezuela, and Russia (Babina et al. 2023, Laudati and Pesaran 2023, Kilian et al. 2024b, Rodríguez 2025). Regardless of formal restrictions, untracked oil continues to achieve world markets, calling into query the true effectiveness of sanctions in curbing exports. These hidden shipments can, in flip, affect world oil provide, influence power costs, and reshape commerce patterns extra considerably than official information alone may point out.
In a latest paper (Fernández-Villaverde et al. 2025), we current a novel ship clustering mannequin to detect darkish transport linked to sanctioned oil transport. By analysing vessel-specific traits, evasive behaviour throughout sign gaps, and navigational anomalies, we quantify unauthorised tanker shipments throughout the worldwide crude oil fleet. Utilizing this information, together with state-of-the-art strategies for causal inference in time sequence, we examine how sanctions and darkish transport have an effect on oil flows, costs, and financial exercise in each sanctioning and non-sanctioning international locations.
What’s Darkish Delivery?
Darkish transport happens when vessels deliberately disable or manipulate their automated identification system (AIS), concealing their location, course, and pace from world monitoring programs. These AIS gaps allow tankers to load or unload oil with out official reporting, typically in areas with weak sanction enforcement, reminiscent of worldwide waters.
Determine 1 Satellite tv for pc imagery of a direct go to to a suspicious port and a ship-to-ship switch
Notes: The left panel shows satellite tv for pc imagery of the darkish ship Roma (IMO: 9182291) at Kharg Island, Iran, on 20 August 2022, throughout a interval when its automated identification system (AIS) transceiver was off. Dashed white arrows point out the vessel’s estimated trajectory through the information hole. The correct panel reveals satellite tv for pc imagery of an unauthorised ship-to-ship switch between two darkish ships, Abyss (IMO: 9157765) and Shanaye Queen (IMO: 9242118), on 28 January 2022 within the Persian Gulf, with dashed white arrows marking their respective trajectories. All three darkish ships had been detected utilizing our ship clustering mannequin.
Tankers might both load oil immediately from sanctioned ports whereas their AIS indicators are off or conduct ship-to-ship transfers between darkish vessels (see Determine 1). By working covertly, they capitalise on premiums supplied by sanctioned producers striving to keep up exports. This mechanism explains how oil from restricted international locations continues to achieve world markets regardless of sanctions.
With seaborne transport representing over three-quarters of world crude oil commerce (US Power Data Administration 2024), these evasive techniques can considerably distort official commerce statistics. Our analysis presents a scientific strategy to figuring out these covert actions and assessing their broader financial influence.
A ship Clustering Mannequin to Determine Darkish Ships
Our research employs a multi-attribute ship clustering mannequin based mostly on intensive AIS data protecting the worldwide crude oil tanker fleet from 2017 to 2023. As a substitute of counting on a single attribute, reminiscent of vessel age, the mannequin integrates three key layers of study:
Vessel traits, together with the tanker’s age, the variety of vessels operated by the identical firm, and flag registration. We discover that vessels with ‘flags of comfort’ (i.e. flags from jurisdictions with decrease oversight) and older ships usually tend to exhibit suspicious behaviours.
Journey-level info. We monitor every tanker’s voyages from port to port, noting origins, locations, and whether or not it seems close to sanctioned international locations throughout an AIS hole. This trip-level view clarifies when a tanker is more likely to be choosing up or delivering cargo with out correct disclosure.
Motion dynamics. The mannequin additionally analyses the frequency, length, and timing of AIS darkish intervals, together with anomalies in pace or heading. Crucially, it identifies potential ship-to-ship transfers by detecting situations the place two vessels go darkish concurrently whereas in shut geographical proximity.
By integrating these options, we assign a ‘darkish rating’ to every vessel and journey. A tanker that hardly ever goes darkish and avoids sanctioned areas throughout AIS gaps is classed as ‘white’, indicating a low chance of involvement in covert oil transport. Conversely, a vessel with a number of suspicious voyages, extended AIS gaps, and routes carefully aligned with sanctioned producers is flagged as ‘darkish’.
This strategy minimises dependence on exterior information, reminiscent of satellite tv for pc imagery or possession data, which can be incomplete or pricey. As a substitute, it leverages extensively obtainable AIS information and a structured methodology to systematically detect darkish transport throughout the worldwide fleet.
Monitoring the Flows of Darkish-Shipped Oil
We discover that darkish transport is way from a marginal exercise. As proven in Determine 2, from 2017 to 2023, a mean of seven.8 million metric tonnes of crude oil per thirty days had been exported through darkish ships from Iran, Russia, Syria, and Venezuela – equal to roughly 43% of whole world seaborne crude exports reported in official UN Comtrade statistics. The prevalence of darkish transport additionally rises considerably following main coverage shifts, such because the US withdrawal from the Joint Complete Plan of Motion in 2018 and the imposition of oil embargoes and value caps on Russian exports in 2022–2023.
Determine 2 Oil exports of sanctioned international locations by darkish ships vs world seaborne oil exports on document
Notes: The stacked bars signify estimated month-to-month crude oil exports transported by darkish ships from Iran, Russia, Syria, and Venezuela. The stable blue line reveals world seaborne crude oil exports, sourced from the UN Comtrade database (HS code 2709: petroleum oils and oils from bituminous minerals, crude). Each sequence are measured in million metric tonnes.
From late 2022 onward, information on Russia means that whereas formally recorded exports declined following Western sanctions, shipments through darkish vessels greater than doubled. This rechannelling of oil flows seems to have offset a lot of the anticipated provide contraction. By successfully growing oil provide, these untracked shipments might exert downward strain on world oil costs.
One other key perception is {that a} vital share of this oil in the end reaches non-sanctioning international locations (e.g. India), typically at discounted costs (Hilgenstock et al. 2023, Kilian et al. 2024a). This realignment underscores how oil can bypass formal restrictions when substantial patrons stay outdoors the sanctioning coalition.
(Un)supposed Macroeconomic Results
To evaluate the influence of those flows on world financial exercise, we use native projections (Jordà 2005, Barnichon and Brownlees 2019) to analyse how adjustments in sanctioned oil flows correlate with shifts in industrial manufacturing and costs within the US, the EU, and China.
For the US, as a web oil exporter, the elevated availability of discounted, dark-shipped oil helps preserve world costs down. Within the brief run, this depresses US oil manufacturing and associated sectors, as decrease world costs scale back revenues. Nonetheless, US shoppers and downstream industries profit from cheaper imported items – significantly from China, the place decrease power prices improve manufacturing competitiveness. The online impact is blended: a short-term contraction in US energy-related industries, offset by long-term positive factors in broader non-energy sectors because of decrease enter prices from non-sanctioning international locations.
As a web oil importer, the EU faces greater power prices if sanctions briefly drive up recorded world oil costs. Nonetheless, rising export demand from China – whose manufacturing advantages from cheaper power costs – gives a lift to EU producers. The result’s a fancy dynamic of demand-driven inflation and output enlargement, the place some sectors profit from China’s progress whereas others battle with greater power prices.
Entry to discounted oil imports lowers power prices in China, stimulating home manufacturing. This, in flip, boosts industrial output in each the US and the EU via elevated commerce, as Chinese language producers profit from cheaper inputs and heightened competitiveness.
Relevance for the longer term
Our analysis highlights how oil sanctions have far-reaching mixture results past the focused economies, typically unexpectedly benefiting international locations engaged in world commerce. These insights are essential for policymakers, who should account for the supposed and unintended penalties of darkish transport on the worldwide provide chain when designing and adapting oil-related sanctions.
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