Prime Minister’s participation in Helsinki underscores maritime-security aims, with the JEF members having conducted operations against shadow fleet vessels.

London aims to close UK waters to shadow fleet ships, forcing operators to reroute to longer, more expensive paths or risk interception.

Britain’s Prime Minister authorized maritime forces to board and detain Russian vessels suspected of belonging to Moscow’s shadow fleet, which exports oil in defiance of Western sanctions.

The move is part of a broader sanctions enforcement effort targeting Russia’s shadow fleet, a network of aging tankers used to bypass sanctions amid Moscow’s war in Ukraine.

London has sanctioned around 544 shadow fleet vessels, noted for opaque ownership and environmental and marine risks posed by aging, poorly regulated ships.

At the Joint Expeditionary Force summit, leaders will discuss shared security in the High North, the Ukraine war, and defense spending, with tensions over military funding between governing Conservatives and Labour.

JEF members include Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, the Netherlands, Norway, Sweden, and the United Kingdom.

The action is part of the JEF’s broader effort to counter Vladimir Putin’s incursions and ties to upcoming talks in Helsinki with northern European leaders.

The decision precedes the JEF Summit in Helsinki, where Britain seeks greater coordination on seizing shadow fleet vessels.

The plan could involve fast-roping from helicopters or grappling hooks to seize tankers during transit in UK waters, including the Channel.

Defense Secretary has signaled potential military options to seize oil from sanctioned ships, with proceeds potentially supporting Ukraine.

Officials emphasize defending sovereignty, supporting Ukraine, and maintaining security in the High North as core motivations behind the operation.