While I can understand Poland's desire to have nuclear weapons available, this seems like it would be a really provocative step towards Russia. Nuclear weapons positioned that close to Russia will raise the threat of a nuclear first strike against Russia. Even without an unstable strongman in charge of Russia, it's easy to see how a Russian government would be uncomfortable with this. At the same time, with an unstable strongman in charge of Russia, the provocation may not matter. Putin has proven he is willing to invade his neighbor and slaughter thousands, without provocation. So, I'm sure Poland isn't as worried about provocation as they are defense.