Greek tanker operators shipping approved Russian oil exports are expected to continue doing so despite a new wave of tougher sanctions by the European Union that will further tighten restrictions, shipping sources said on Friday.

Much of Russia’s oil is now exported by a so-called “shadow fleet” of unregulated tankers, but shipping data shows Greek-owned ships, part of the world’s largest tanker fleet, have also been carrying some of the share of Russian crude that does not fall under sanctions or exceed the price cap.

The EU on Friday agreed an 18th package of sanctions against Russia over its war in Ukraine, including measures aimed at dealing further blows to its vital energy industry.

Central to the measures is a price cap under which the EU will seek to prevent purchases of Russian crude at less than 85% of the average market price. This currently puts the cap around $47.60 a barrel, far below the largely ineffective $60 cap that the Group of Seven Western powers had sought to impose.

Greek shipping companies, which account for dozens of oil shipments from Russia every month and an estimated 20% of overall trade, will continue to ship as much as they can, said the sources, who declined to be identified due to the sensitivity of the matter.

While it will be more difficult, such transactions remain “doable”, said one source at a Greek shipping company involved in the trade.

“As long as traders keep buying oil at that price, things won’t change much, we’ll respect the new cap.”

Greek shipping ministry officials did not immediately respond to a request for comment.

The U.S. has so far shown no desire to align itself with the EU price cap. Because most oil is sold in dollars, and only U.S. banks can restrict the clearing of dollar payments, this is likely to limit the effectiveness of the EU move.

Nevertheless, it will add complexities to sanctions-compliant trading in Russian oil by European firms.

“Similar to the previous requirements, they will need to comply with the new EU price cap and ensure that they are comfortable that they are only trading in price cap-compliant product,” said Leigh Hansson, sanctions partner at law firm Reed Smith.

“We expect that there will be a 90-day wind-down period for the transport, and related services, of Russian crude oil for contracts concluded by July 18.”

Source: Reuters reported by Jonathan Saul and Renee Maltezou and edited by Kevin Liffey