Russia is not even cut off from trade with USA. There are even messages that USA is buying some amount of Russian oil every month.
From the other hand, Russians can buy anything western they want, just with more friction and higher price. Even dual-purpose western components for army are freely available for them.
They are cut off from the American system. The products will leak from both ways unless you impose a strict naval blockade. For some premium, many countries will dodge the sanctions.
From the other hand, Russians can buy anything western they want, just with more friction and higher price. Even dual-purpose western components for army are freely available for them.