On May 13, a mysterious ship named Jaguar sailed through waters near Estonia in the Baltic Sea. This ship, once registered under Gabon’s flag but now sailing without any national flag, was believed to be part of a “shadow fleet.

MILAN — Russia’s detention of a Greek-owned ship that departed from Estonia – days after Estonian forces tried to intercept a Russia-bound tanker – signals Moscow’s willingness to deploy military power more overtly to protect its shadow-fleet, a vital pillar of its war economy, experts say.

Russia detained a Greek-owned oil tanker on Sunday after it left an Estonian Baltic Sea port, the Estonian Foreign Ministry said, adding it had alerted NATO allies to the incident.