Europeans will start impeding vessels from Russia’s shadow fleets when they enter their waters, French President Emmanuel Macron said on Thursday.

“We have decided to take a step forward by adopting policies to impede suspicious ships in our waters,” he told reporters in Copenhagen after a meeting of the European Political Community.

European chiefs of defense staff, in coordination with NATO, will meet in the coming days to “develop joint actions in the coming weeks to implement a policy of obstruction against the shadow fleet,” he added. The gathering will be held in a coalition of the willing format, an initiative driven by France and the United Kingdom provide security guarantees to Ukraine.

Macron’s comments come after French forces on Wednesday arrested two crew members on a tanker suspected of belonging to Russia’s shadow fleet.

Europeans have grown increasingly frustrated as Moscow continues to circumvent international sanctions by surreptitiously transporting and selling its oil to bring in revenue that contributes to its war effort against Ukraine.

“There are 800 to 1,000 ships contributing to the Russian war effort,” Macron said, calling the decision to obstruct vessels as “another step forward in the fight against the shadow fleet.”