On September 1, when the German government publicly blamed Russia for the failed drone attack on Leipzig Airport, it announced a series of retaliatory measures. Among them was a tougher crackdown on the so-called Russian shadow fleet. The term refers to often aging, poorly maintained and inadequately insured vessels, mostly oil tankers, with opaque ownership structures, which Russia uses in an attempt to circumvent sanctions.

But detaining such vessels is far from straightforward, Julian Pawlak, a maritime security expert at the German Institute for International and Security Affairs (SWP) in Berlin, told DW. International maritime law, he noted, is fundamentally designed to protect the freedom of commercial shipping. "The transport of these goods on the high seas is not, in itself, illegal," Pawlak explains. What complicates matters is that parts of this shadow fleet are linked to so-called hybrid activities, including acts of sabotage, espionage, and possibly drone operations and related disruptions."

Germany has not done enough to address the issue so far, argues Sara Nanni, a security policy spokesperson for the Green Party. In a recent interview with DW, she complained: "Russia is financing both its war against Ukraine and its aggressive behavior toward Europe through its shadow fleet." Action must be taken against it, she said. "That is the only thing that could persuade Russia to return to the negotiating table," she argued.