A former officer at a Russian nuclear weapons base has shared a rare account of the high alert status during the first days of Russia’s invasion of Ukraine in February 2022. His testimony also highlights the harsh realities of defying orders,

Russia has stepped up its threats to the West in response. On Tuesday, the 1,000th day of his invasion of Ukraine, Putin signed a revised nuclear doctrine declaring that a conventional attack on Russia by any nation that is supported by a nuclear power will be considered a joint attack on his country.

Intelligence assessments over the past seven months have shown that a nuclear escalation is unlikely to result from a decision to ease restrictions on Ukraine's use of U.S. weapons.

Russian attacks reported across Ukraine with power cuts affecting more than one million people in freezing temperatures.