Senior NATO official: Russian nuclear strike would likely prompt 'physical response'

A senior NATO official warned that a Russian nuclear strike would likely prompt a "physical response" from Ukraine's allies, and possibly from NATO itself.

Such a strike would "almost certainly be drawing a physical response from many allies, and potentially from NATO itself," the official told Reuters.

Russia has hinted several times at the possibility it could unleash weapons of mass destruction in its battle with Ukrainian forces if Putin believes the fate of the country is at risk.