I think the no first uses policy is foolish.
Example:
If china masses a huge army at the mountain passes the option of using a tactical nuke should be on the table.
And be vapourised by the chinese second strike? No chance.
Only countries which do not have sufficient troops at the border have policies like that. For example, the Russian nuclear doctrine is made in such a way that if they are dragged into a war the odds of which are stacked even slightly against them, they'll go nuclear. So if tanks from Germany cross their border and head for Russia, their nuclear doctrine suggests nuclear strikes.
Similar picture for Pakistan, they talk of nuclear retaliation at the drop of a hat. However, this is an untenable posture because if such a first use does happen, the country is bound to be annihilated by the nuclear second strike, which is always going to be many times more intense and massive than first strike. So first use policy is futile and counterproductive