The Poles were attacked from both sides by Germany and Russia. They had treaties with the UK and France, and France had a large land army and they could have at

The Poles were attacked from both sides by Germany and Russia. They had treaties with the UK and France, and France had a large land army and they could have attacked Germany with a legitimate casus beli. The UK had very little capability to actually defend Poland. Once France did not attack Germany, there was indeed not much that Poland could do. The situation is a bit different now. The US can't help with boots on the ground, or with any type of "kinetic response", but it can help Ukraine with intelligence, and maybe a bit of deniable cyber warfare. The US has all the incentives to help Ukraine. Not to the extend of putting soldiers in harm's way, but the US doesn't like Russia becoming 30% larger in terms of population (and therefore military manpower). Moreover, if Ukraine falls, Belarus and Kazakhstan will "voluntarily join the union" in no time. That's not something the US is keen to see happening on the global security chessboard. But still, Putin knows all these things, and he likes his chances. We can only watch and see a grandmaster at play.