An EU army. Impact on Poland

Of course there isn't. Even Czechs and Slovaks couldn't get along, despite speaking mutually intelligible languages.

Well splittng up the country was a poltiical project that did not have majority popular support in either part. Some Czech politicians wanted shut of the poorer Slovaks and the Slovak leader of the time wanted free reign to impose a neo-Soviet model. Fortunately the Slovaks wised up after a few years and kicked him to the curb but not in time...

Also, the move has not been good for Slovak, while Czech is still widely understood in Slovakia (with constant TV and other media exposure) Slovak has all but disappeared from public life in the CR and younger Czechs have real problems understanding it. The mutual intelligibility depends on constant exposure which was a feature of Czechoslovakia and not the Czech republic.

Isn't this rather related to Slovak being a mess in terms of spoken dialects? I spoke to someone from Usti nad Labem a while ago about it, and she reckoned that while the Western Slovak dialect (or essentially TV language) was simple to understand because it was more or less similar to how they speak in Moravia, the messy Eastern dialects were much worse for her. I noticed it when I was there last year - I can get by in places like Bratislava and Zilina, but in Presov and up towards Svidnik/Bardejov, it just sounded like a funny Polish dialect and not like Slovak at all.

I've heard some very weird spoken Slovak, some dialects sound very Ukrainish (with a Greek style gamma instead of a voiced h in words like kniha).

But I was referring more to official technical vocabulary, Czechs used to have exposure to it and don't anymore. This means, for example, that Czechs vacationing in Slovakia can get by on everyday topics but if they get sick and need to see a doctor then they're likely to have real communication problems.

you are wrong. We all have choice to support our own civilization or to fight against her. If there are few Slavic countries that defend themselves from hostile non-Slavs, then yes, Slavic-brotherhood do exist.