On Background: Putin's nuclear threat

Russian President Vladimir Putin has announced an update of his nuclear doctrine, lowering the threshold for the use of nuclear weapons.They could now be deployed – Putin says – if a nuclear-armed nation supports Ukraine in the use of long-range missiles against Russia.The west has been weighing whether to give Ukraine long-range missiles that can reach deep into Russia. Putin’s clear warning to the west is that this could trigger nuclear war.David Speers speaks to Ukraine’s Ambassador to Australia Vasyl Myroschnychenko about whether the conflict is at a tipping point.