Russia is telling customers of its Sakhalin-2 LNG plant in the country’s far east to pay in rubles or other currencies if sanctions lead to issues with payment in U.S. dollars, in the latest twist around the reshuffling of the project’s operator.

Buyers must use alternative currencies — including the ruble, euro, yen or British pound — if payment in dollars, as set in contracts, can’t be processed, according to documents seen by Bloomberg.

The demand adds complexity for customers of the Sakhalin-2 project, mainly in Japan and South Korea, as they assess changes that Russia is proposing for deals from its oldest liquefied natural gas facility.