NATO clearly answers this, No First Use. Individual countries can deploy though. US says no first use except in response to WMDs (so bioweapons or chemical we

NATO clearly answers this, No First Use. Individual countries can deploy though. US says no first use except in response to WMDs (so bioweapons or chemical weapons). By clearly defining it, it makes it less likely to escalate to accidental MAD. We know the line, Russia knows the line. And they know the potential consequences should they choose to cross it. On the other hand Russia has recently been opening their doctrine to allow nuclear strikes in response to conventional attacks. Further they threaten nuclear responses. They're intentionally blurring the lines because they feel they can get away shenanigans in the confusion.