Catholic belt (Intermarium v2.x)
Hmm...

The Catholic Intermarium 2.0 looks incomplete - without Finland, Latvia, Estonia, Romania, Ukraine and Bulgaria. It consists of only six countries (Lithuania and Hungary included conditionally) and Poland has higher population and GDP than the other five members combined. Not much of a shield, unless Poland gets a lot of nukes.
However, the very idea of a Catholic Union seems plausible only before one realises that there are very few genuinely Catholic countries in Europe these days. Poland, Italy, Slovakia, Croatia, Slovenia and Portugal can still be counted as reasonably Catholic. Others, even if they still theoretically have Catholic majority, are too secularised these days.
Oh, I forgot about San Marino, Malta, Liechtenstein, Andora, Luxembourg and Vatican - sorry. ;)