KSE Institute has published “The Impact of Shadow Tanker Designations,” an analysis of how US and EU sanctions against shadow fleet vessels affect the maritime transport of Russian oil.

The analysis shows that these measures are disruptive, but that their effects differ in both scale and mechanism. US sanctions impose immediate and binding constraints that force a restructuring of logistics and sharply reduce activity, while EU measures operate more gradually, sustaining pressure over time while allowing trade to continue through alternative channels.

Key findings:

Both sanctions regimes reduce volumes markedly. US sanctions trigger an immediate and steep decline: crude oil and oil product shipments fall by more than 70% following designation, with the former partially recovering over time and the latter effectively disappearing. The effect of EU sanctions is more gradual but, ultimately, volumes decline more than in the US case: crude oil shipments end up 55% lower than before sanctions and those of oil products 64%.

US and EU sanctions trigger fundamentally distinct operational disruptions: US sanctions impose binding constraints that force a reorganization of transport chains: voyage durations increase sharply, ship-to-ship (STS) transfers become a primary logistical channel, and access to ports contracts, resulting in a less efficient system that channels flows through a small number of hubs and relies on offshore handling and concealment. Over time, crude oil volumes partially recover but within a narrower and more opaque system, while, for oil products, the impact is so severe that trade largely collapses altogether. Vessels rapidly exit established flag registries and shift first toward false flags and high-risk jurisdictions, before consolidating under the Russian registry, which becomes the dominant channel for post-sanctions shipments.

EU sanctions, by contrast, lead to more incremental adjustments. Vessels continue to operate within an existing network, with moderate increases in voyage duration and more limited changes in STS activity. Rather than forcing systemic disruption, EU measures induce adaptation within a still-functioning trading system. While China and India remain the main destinations, independent Chinese refineries willing to process higher-risk cargoes take on a larger role. The transport network remains relatively broad, with flows redistributed across multiple ports rather than concentrated in a few hubs. Vessels respond to sanctions by diversifying across alternative flag registries, with some increase in false flagging but no shift toward a single dominant registry.

The analysis is based on a sample of 144 US-designated and 195 EU-designated vessels, with no overlap between groups in order to isolate the effects of each sanctions regime. It applies an event-study framework with 180-day observation windows before and after designation, excluding wind-down periods, and incorporates a later post-period for vessels sanctioned longer. The study evaluates changes across multiple indicators–including transported volumes, voyage duration, transport efficiency, STS activity, port access, and flagging behavior–allowing it to distinguish sanctions-specific effects from broader market trends.