Ukraine latest news: Thousands of Putin's troops 'call Ukrainian surrender hotline' - as Russian front line 'begins to collapse'

Foreign policy expert Ian Bond, from the Centre for European Reform think-tank, says the West needs to stop being - and sounding - afraid.

This is what he told the Doomsday Watch podcast:

"Nothing is as provocative to Putin as weakness, so the more the West says 'we are afraid that Russia might use nuclear weapons', the more likely it Putin is to continue making the threat of using nuclear weapons - and perhaps even use one or two to demonstrate he really means it."

Bond says the message to Russia, which could be delivered privately, should be "please understand that if you go nuclear, we will regard the gloves as being off".

While accepting that no one could "absolutely rule out" Russia would use nuclear weapons, he outlined evidence from the conflict so far that Mr Putin wouldn't go there...

"Not only have the Russians not responded in any particular way to attacks on Crimea, but even on absolutely undisputed territory, in the Belgorod oblast - there have been Ukrainian strikes and the Russians have not responded to that in any particularly different way.

"We should stop frightening ourselves with the bogie man that if the Ukrainians drive the Russians out, the Russians are going to go nuclear, I just don't buy that."

Bond also identified a problem facing the Russians as this war continues, regardless of the partial mobilisation announced last months.

"Just sending a lot of people with rusty rifles into battle isn't going to do the job. There are steps, allegedly, to get the Russian defence industry to ramp up production but over the last 30 years the Russian defence ministry has become quite dependent on foreign components, foreign machine tools.

"It's not going to be easy for Putin to ramp up production of equipment. So you're going to be pulling older and older kit out of storage, which takes more and more time to put into any kind of condition to use and is no match for the more modern weapons NATO is supplying to Ukraine."

The question then, Bond says, becomes: can Mr Putin get the weapons from another country?

We know Russia has been getting drones for Iran. Bond says they have been "useful" already in damaging facilities in Odesa, but he doubts they are a "game changer".

"Will the Chinese step in? They've been reluctant to get directly involved in this conflict so far.

"I don't see this mobilisation as a game changer. It will extend the war, it will increase the casualties on both sides. especially on the Russian side. But is Putin going to get a decisive breakthrough to Kyiv by sending another 100,000 men into the meat grinder? No, I don't think he is."