If the EU contributed conventional only weapons and personnel to be used only as territorial defense in Ukraine, that is, never shooting a single shell outside

If the EU contributed conventional only weapons and personnel to be used only as territorial defense in Ukraine, that is, never shooting a single shell outside of Ukraine, Russians would still have a hard time justifying going at war with the EU, NATO, let alone using nukes. My point is that there's still some room left to help Ukraine militarily without serving Putin the pretext to declare war around the world. Sanctions need a lot of time to become really effective and something must be done to buy Ukrainians more time. I don't see what could be more effective than military help.