Russia will halt gas supplies to buyers from ‘unfriendly’ states unless they switch to payments in rubles from April 1, President Vladimir Putin said, the latest strike in a struggle with Europe over energy sales.

“To buy Russian gas, they need to open ruble accounts in Russian banks,” Putin told officials in a televised speech Thursday. “It is from those accounts that gas will be paid for starting April 1. If such payments aren’t made, we will consider this a failure by the client to comply with its obligations.”

Buyers should open special accounts in state-controlled Gazprombank to allow foreign currency to be swapped to rubles for settlements, according to an order signed by Putin.