Russia is already assassinating and sabotaging in NATO countries, which are legal acts of war too.

They're more grey-zone, since many countries do low level hostilities below threshold of war, which is different end of spectrum than blockade that's closer to unambiguous open warfare.

think of being kura-murza or yashin, both in jail for being political dissidents, only to find our you are being exchanged evil people you are fighting against.