EU will only be able to defend itself if it stays united, which is not a given in the future. There is no guarantee that part of the EU will decide not to bloc

EU will only be able to defend itself if it stays united, which is not a given in the future. There is no guarantee that part of the EU will decide not to block any joint military action for either fear of retaliation from russia or because of separate peace agreements with it. You can see that right now US incites division in multiple ways: Musk in Germany, Republicans in UK, Trump in Denmark. These are all coordinated attacks with the same strategic goals.