Might Vladimir Putin use a nuclear weapon? The calculations are changing

I think the risk of a nuclear threat right now is pretty low — as long as Russia feels it's winning," said Malcolm Chalmers, deputy director at the Royal United Services Institute, a London-based defence think-tank. ..."We started the war with this rather artificial distinction between defensive weapons, which were OK — anti-tank weapons — and offensive weapons like tanks which were not OK. And we've moved substantially beyond that," he told CBC News in an interview. "Now the United States is saying: 'We'll only supply particular weapons if they're not used against Russia's own territory.'"