Russian President
Vladimir Putin is set to demonstrate his willingness to use
weapons of mass destruction with a nuclear test on Ukraine's borders, Nato is believed to have warned its members.
The Kremlin has been signalling its readiness for a significant escalation as
Russia loses ground on the battlefield.
Fears over Putin's earlier hints that he might resort to such tactics heightened on Monday with claims that a train operated by the secretive nuclear division was destined for Ukraine.
Konrad Muzyka, a Poland-based defence analyst, said the train, spotted in central Russia, was linked to the 12th main directorate of the
Russian ministry of defence and that it was "responsible for nuclear munitions, their storage, maintenance, transport, and issuance to units".