One day passed, and the support of the Bittrex exchange gave soothing comments to the Russians:

The new terms of service change nothing with regard to economic sanctions. U.S. law prohibits us from doing business with residents of North Korea, Iran, the Crimean region, Syria, and Cuba. Additionally, we cannot do business with people against whom there are economic sanctions levied by the U.S. government. The federal government publishes lists of those individuals, and we screen against those lists on account opening, so if you are a current customer of Bittrex, that means you are not on the list.

So far so good))