A little earlier, we reported on a British minister’s response to Vladimir Putin’s threat in a speech today to use nuclear weapons.

Washington has now offered a response to the Russian president’s comments, with state department spokesperson Matthew Miller saying the US does not have any sign that Russia is preparing to use a nuclear weapon – but will continue to monitor the situation carefully.

“It is not the first time we have seen irresponsible rhetoric from Vladimir Putin,” he said.

“It is no way for the leader of a nuclear armed state to speak.”

Mr Putin earlier today told Western countries they risked provoking a nuclear war if they sent troops to fight in Ukraine.