Why cryptocurrency would be a "useful tool" for Russia evade western economic sanction?
as long as we define "cryptocurrency" as "decentralized," then it's useful because no central authorities can prevent payment, so sanctions cannot be easily enforced. centralized currencies like XRP/ripple or USDT couldn't be used, though, because they have centralized administrators and validators who could enforce sanctions.
because BTC is highly transparent and not anonymous, it might not be ideal for dodging sanctions, but combined with elaborate networks of shell companies, it could certainly help to give russia an edge in the "cat-and-mouse" nature of sanctions enforcement. when more private cryptocurrencies like monero have higher global trading volumes, they could provide a further layer of obfuscation to their sanction evading strategy.