"Russia's nuclear doctrine allows the use of such munitions if weapons of mass destruction are used against it or if the Russian state faces an existential threat from conventional weapons. We will certainly make use of all weapon systems available to us. This is not a bluff," Putin warned.

The above statement is an operative excerpt from what Russian President Putin said. The term "existential threat" directly implies that if 'red lines' defined by Russia are likely to be crossed, Russia reserves the right to use nuclear weapons.

Ironic but true, except for the usage of different words, Pakistan leadership has also expressed a similar determination to use nukes if the Indian military with conventional weapons was in a position to threaten Pakistan.

Western Nations Crossing The 'Red Line'