Putin 's nuclear sabre rattling is as convenient for NATO as it is for him.
The West is terrified of the idea of going to war with Russia. A war for which they are ill-prepared on the ground and even more so in air defence.
Nor is there any political stomach in any NATO nation. It is easier on the one hand to send weapons and equipment which cannot shift the balance of Russia’s military superiority, and on the other to continue financing Putin’s war by buying his gas and oil.
Meanwhile fear of nuclear escalation is nothing more than an excuse for failing to intervene.

In reality NATO leaders know as well as he does that Putin is bluffing when he talks about nuclear conflagration. Some so-called experts say he is deranged and unpredictable and might unleash apocalypse on the west at the drop of a hat. In fact he is logical, rational and measured.
He won’t send in the nukes in retaliation for western arms supplies to Ukraine and nor would he if NATO took part in the conflict there. He just wants to scare the west into keeping out of his war including supplying aircraft and heavy weapons to Kyiv.
Putin’s invasion of Ukraine is all about his legacy as a Russian Tzar. He wants to go down in the history books as the man who restored Russia’s imperial glory.
The inevitable consequence of the escalation he keeps threatening would be a nuclear winter descending on Russia. He knows that and it is the opposite of what he wants.