Sir Michael Fallon is too late to veto the European army

I found Sir Michael’s statement that he will continue to veto a European army all the time the UK remains in the EU perplexing. Now we are leaving I do not see it is any business of ours to veto what they are going to do when we leave. It just annoys the very countries we wish to be friends with as we depart.
I do wish we would just get on and leave and stop paying our contributions. If we rightly do not go to conferences like Bratislava why do we help pay the bills?
Nor do I understand how Sir Michael can veto something that already exists and the UK has accepted. The EU has established eighteen battle groups, each at battalion strength, with a rota so that any two of them can be deployed at any time by the European Council. As the EU’s own website sets out “The battlegroup concept provides the EU with a specific tool in the range of rapid response capabilities.”
The UK has played its part on the multinational rota to provide forces. None are currently deployed but they could be.
There is also already a Eurocorps, mainly French and German, stationed in Strasbourg with 1000 soldiers.
In parallel the EU does have naval forces in theatre today. Again the UK is signed up to this. Two of the 7 ships on Operation Sophia in the Mediterranean are UK vessels according to the EU website. There is a also a 4-6 vessel force off Somalia in Operation Atalanta which receives UK assistance.
Just as many of us pointed out in the referendum campaign, there is a European military capability and they do wish to grow a bigger and more active army. Some Remain spokesmen told us this was all nonsense. The conversation at Bratislava reminds us that there are already EU forces and they do wish to strengthen them and make them more active.
The UK should leave well alone and ask itself whether it wishes to carry on contributing after it has left. 4 non EU countries are involved in these forces at the moment. Perhaps our defence Secretary could give us some guidance on this more interesting issue, which will be his call along with the PM.