Senior Russian security official Dmitry Medvedev said on Tuesday that if the West supplied nuclear weapons to Ukraine then Moscow could consider such a transfer to be tantamount to an attack on Russia,

The U.S. decision to allow Ukraine to fire American weapons deeper into Russia has not increased the risk of a nuclear attack, which is unlikely, despite Russian President Vladimir Putin's increasingly bellicose statements,

Deploying British troops to Ukraine could be like a "declaration of war against Russia" and cause a "nuclear exchange", an expert has told the Daily Express UK.