The most urgent question for everybody is, to whom would this entity be answerable? One could suggest the Parliament, the President of the European Commission, or the President of the European Council. The best would be either the Parliament or someone chosen by the European Parliament, or a president directly elected by the European people, because it would be the most democratically legitimate.
Having decided who will be the political leader of the European Army (EUA), the next question that arises is what this leader can and can’t do. That is, can they declare war? Do they need parliamentary permission to move troops inside the borders of Europe? And outside of them? And so on. This, in the end, can be summed up in the question: What powers would this leader have and which of their decisions are dependent on parliamentary approval?
In order for the EUA to even have a chance of being effective, European nations would have to cede their right to declare war to the political entity that is also in control of the EUA. Since, if this weren’t the case, and these competences were shared, it would make the EUA significantly dysfunctional. Let’s assume a nation declares war on another nation, the first nation being in the EU, whereas the second is outside of NATO. Two courses of action are now possible, either the EUA participates or it doesn’t.
In the first case, one may need to worry about creating a precedent where nations, after declaring war, expect direct and/or indirect support from the EUA, leading to a situation where a minority can force the people of Europe into an unwanted war.
In the second case, the cohesion of the Union will be put into question and possible grievances created between its members. Furthermore, even if at first the EUA were not to participate, the sovereign territory of this nation would be under the defence of the EUA, making an attack against it an attack on all of Europe, leading to the participation of the EUA in the conflict.
As this thought experiment shows, for the EUA to be realistic, the European nations would also have to give up sovereignty on foreign policy matters, which is in many cases already a reality (consider the common seat we share at the WTO). But the change would have to be more fundamental. If these steps were to be taken, Europe would, de facto, be a federation. It is fundamental to understand that this step would be a necessity.
Another step to be taken into account would be NATO membership. In what form would the EUA be integrated into NATO? Could it take over duties up until now delegated to the US, such as the fight against insurgencies in African nations like with Nigeria and Boko Haram? How would the EUA affect our role in the Middle East?
Another problem that the EUA could face is the number of languages spoken in our continent. The structure and recruitment of the EUA has also a number of issues.
Let’s consider the need for communication in armed forces. Information must travel up and down the chain of command unchanged and as fast as possible. This might necessitate the existence of a cutoff point, that is, a point down the chain of command where it may be desirable to field soldiers who speak either the same, or sufficiently similar languages, so that communication is not excessively hindered (Italian and Spanish, for instance). This may not be such a big issue in the officer corps since it is usually university educated, and thus probably versed in the English language.
Currently European militaries, at least Western European militaries, have great personnel problems. This would probably be transmitted to the EUA and would be more acute for it since Europe as a project doesn’t have as wide a support base as the current European nation-states. This might be alleviated through some kind of mandatory military service that would support a professional army.
Financing the EUA would also present its own issues, stemming mainly from the way that the EU is currently funded, that is, a certain percentage of VAT and a GDP-dependent quantity. These funds are quite probably not sufficient for an EUA of any significant size. This means that the EUA would either be dependent on the goodwill of the European nations and receive a percentage of funding of each national military, or the EU would have to introduce taxes in order to pay for it.
It is also important to note that depending on how these were to be implemented, the EUA could be the sole force in the EU or an equivalent force to national militaries. The first case presents the problem of a single point of failure; if the armed forces were to be overtaken by malicious internal actors, there would be nothing to act as a counterweight. The second case would mean duplication of institutions and waste of resources.
Finally, a point having more to do with Europe and our mindset, is whether or not we have the stomach for being a world power. That means, will we have the stomach to send our sons, brothers, fathers, to die for the freedoms, rights, duties and values that underpin Europe? Will we defend them in our sphere of influence? If we are not prepared to do so, whatever we build will be a waste of brains, energy and money. If we find it in us to implement the EUA, then we have to be vigilant.