Another day, another bloodcurdling threat from Vladimir Putin. The Russian president used his annual televised address to warn the west that he was prepared to defend his country, if necessary, by using nuclear weapons.

“They should eventually realise that we also have weapons that can hit targets on their territory,” Putin said, clearly referring to plans by some of Ukraine’s allies to supply medium- and long-rage missiles that could strike targets within Russia. “Everything that the west comes up with creates the real threat of a conflict with the use of nuclear weapons, and thus the destruction of civilisation.”

There has been a discernible sense of urgency about western discussions of Ukraine over the past fortnight. The loss of the town of Avdiivka, a key strategic position close to Donetsk, after weeks of heavy fighting and massive losses on both sides, has set off something of a domino effect in the area. Russia has used the momentum to push the frontlines several miles to the west as part of its winter and spring offensive.

In the previous Ukraine recap, we noted that Joe Biden has managed to get his US$95 billion (£75 billion) aid package through the US Senate. But the package still has to pass the House of Representatives, whose speaker, Mike Johnson, has yet to confirm it will even be given a vote. It’s clear from military reports emerging from Ukraine that the lack of ammunition is rapidly becoming an existential crisis.

Putin also probably had in mind the statement by the French president, Emmanuel Macron, at a security conference in Paris on February 26, that while there was as yet “no consensus” among Kyiv’s western allies about committing troops to the defence of Ukraine: “Nothing should be excluded. We will do whatever it takes to ensure that Russia cannot win this war.”

Since Vladimir Putin sent his war machine into Ukraine on February 24 2022, The Conversation has called upon some of the leading experts in international security, geopolitics and military tactics to help our readers understand the big issues. You can also subscribe to our fortnightly recap of expert analysis of the conflict........

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