Russia has warned it may deploy naval forces in response to European seizures of vessels from its so-called shadow fleet, according to the Kyiv Independent, escalating tensions in the Baltic and North Sea regions where multiple European nations have detained Russian-linked ships.This threatens to militarize sanctions enforcement in European waters. The shadow fleet isn't just about oil revenue—Western intelligence has linked some vessels to sabotage of undersea cables. Russia's threat to provide naval escorts would mark a dangerous escalation in the economic war parallel to the shooting war in Ukraine.The shadow fleet consists of aging tankers, many operating without proper insurance or transparent ownership structures, used by Russia to circumvent oil export sanctions imposed after the invasion of Ukraine. These vessels allow Moscow to continue selling crude oil and petroleum products to willing buyers while evading price caps and other restrictions.European authorities have grown increasingly aggressive in targeting these ships. Finland, Estonia, and other Baltic states have detained vessels suspected of sanctions violations. In several cases, authorities have also investigated possible links to sabotage of critical infrastructure, including undersea communications cables that have suffered mysterious damage in recent months.The Kremlin's threat to deploy naval protection for these vessels represents a significant escalation. If Russia were to provide military escorts for shadow fleet tankers, it would create potential for direct confrontation between Russian and NATO naval forces in European waters. Such encounters carry inherent risks of miscalculation or escalation.To understand today's headlines, we must look at yesterday's decisions. The shadow fleet emerged as Russia's response to Western sanctions, but it has become something more—a tool for projecting power and creating vulnerabilities in European infrastructure. The vessels themselves are often barely seaworthy, creating environmental risks, while their suspected involvement in sabotage operations represents a hybrid warfare threat.European officials face difficult choices. Backing down from seizures would undermine sanctions enforcement and signal that threats of military force can deter legitimate law enforcement. Continuing or expanding seizures risks the very confrontation Russia has threatened, with all its attendant dangers.The threat also exposes divisions within Europe. Baltic states, with their geographic proximity to Russia and historical experience of Soviet occupation, tend to favor aggressive action against the shadow fleet. Other European nations, more distant from the immediate threat, may be more cautious about policies that could trigger military confrontation.What makes this particularly complex is the legal ambiguity. Russia claims its vessels have every right to transit international waters and that European seizures violate maritime law. European authorities counter that sanctions compliance is a legitimate basis for detention and that suspected sabotage justifies investigation. Neither side is likely to accept the other's legal interpretation.The situation could escalate further if Russia follows through on deployment threats or if European nations expand their enforcement efforts. The Baltic Sea, already tense due to the Ukraine conflict and NATO expansion, could become a theater for direct confrontation that neither side ostensibly wants but both seem willing to risk.