Starting in late September, Russia had unveiled its expanded nuclear doctrine which proposed a lowered threshold for Russian strategic forces' use of nukes. This was due to the "emergence of new sources of military threats and risks for Russia and our allies" - amid fiercer drone and missile attacks coming across the border from Ukraine. This change in nuclear doctrine has now been formally signed into effect by President Vladimir Putin on Tuesday, two days after President Biden authorized Ukraine to begin conducting long-range strikes inside Russia with US-made missiles. https://www.zerohedge.com/geopolitical/lavrov-says-west-escalating-conflict-just-after-putin-signs-nuclear-doctrine-expanse