hello, i'm maryam moshiri. you're watching context on bbc news. russia says it will stop supplying gas to european countries it deems �*unfriendly�* — unless they pay for it in roubles. vladimir putin has signed the decree which will take effect on friday. european states are calling it blackmail. the financial system of western countries is being used as a weapon. the assets in dollars and euros are frozen so it makes no sense to use the currencies of these countries. meanwhile, president biden orders a major release of oil from america's strategic reserves in a bid to bring down prices at the pump. tonight with the context, orysia lutsevych, head of chatham house s ukraine forum and angela stent, senior fellow at the brookings institution and author of putin s world .