It’s tough being a country on a natural invasion path with no significant natural borders.
Only to the south. I think they could handle an invasion from Slovakia pretty easily.
They should consider a Swiss or Baltic defense model base on full citizen deployment and guerrilla warfare.
That was true in 1939 but no longer. To the south Poland has the Carpathian mountains. To the north the Baltic sea. To the West the Oder-Neisse river borders. To the east Belarus and Western Ukraine are bulwarks. The Russian attacks on the Ukraine have ended up making Western Ukrainians as fervently anti-russian as they were anti-Polish. So a buffer state. And the Belarussians want to balance themselves between Mosccow and Europe