Ban, arrest or damage "shadow fleet" tankers that transport Russian oil. Control their supply chain e.g. stop selling them spare parts for stolen planes. There are many things, all the way to taking hostages, but EU needs to grow some spine to do that.
Fully close the border with russia? Permanently deny any boat that makes port in russia access to EU ports, I could go on
Ban, arrest or damage "shadow fleet" tankers that transport Russian oil. Control their supply chain e.g. stop selling them spare parts for stolen planes. There are many things, all the way to taking hostages, but EU needs to grow some spine to do that.