It's no secret why Vladimir Putin has rolled out the red carpet for Kim: the Kremlin's forces are running out of artillery shells and North Korea has huge stocks of ammunition that could be for sale.

But what would Pyongyang want out of any deal?

Sky News spoke to Christopher Green, assistant professor at Leiden University in the Netherlands and an expert on North Korean society.

He says there are three strands that cover what the secretive country might stand to gain from any deal with Russia: military and space technology, political benefits and economic benefits.

Military satellite technology

North Korea has failed to launch two satellites so far this year, Dr Green says, giving the impression they need some help.

"Of course what North Korea wants to launch is a military reconnaissance satellite," he says.

This would have military uses - the purpose of which is unclear - but there would be another advantage to having the ability to launch satellites: plausible deniability.

"They also benefit from being able to do peaceful space launching using ballistic missile technology, which allows them to test warhead re-entry technology at the same time."

What about nuclear weapons? Dr Green doesn't think these are seriously on the table.

"I am sure North Korea might be interested in Russian nuclear technology but I am very sceptical that the Russians would actually give them their nuclear technology.

"It would definitely incur the wrath of the US and others and for Russia it seems a risk not worth taking.

"I think neither China, nor Russia nor anybody else who currently has nuclear weapons is particularly keen to see North Korea as a fully fledged member of the nuclear club."

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Showing the world Pyongyang has 'big friends'

As well as getting secrets to space launches, any deal with Mr Putin would serve Kim's interests politically.

It makes him look "statesmanlike" to his domestic audience, Dr Green tells Sky News, and gives the impression he is in "complete control" of the country.

"And it shows North Korea's enemies that it has big friends and that therefore North Korea is somehow safe, comfortable in its own skin with the current geopolitical situation."

For Pyongyang it is "always useful" to have these overt displays of support from China or Russia, he adds.

Finally, North Korea might explore increasing the amount of labourers it sends to work in Russia - who then bring hard currency back to their home country.

But despite this, North Korea wants to remain "fiercely independent", Dr Green argues, dismissing the notion that Pyongyang might send soldiers to aid Russia in Ukraine or help guard its borders.