Almost two weeks ago, what is believed to be a North Korean missile was fired in a Russian attack that killed a Ukrainian family.Ukrainian President Volodymyr Zelenskyy said based on "preliminary data", the missile that killed the family was the result of the alliance between "Moscow scumbags" and Pyongyang's "deranged regime”. "Of course, more examinations will follow, and everything will be verified, but as of now — it is a North Korean ballistic missile," he said.North Korea has previously supplied missiles used in the war, but this suggests Russia may have received fresh stocks at a time when Ukraine's air defences are under strain.Earlier today, Mr Zelenskyy hit out at the growing alliance, claiming Russia "cannot wage war without reinforcements" from North Korea.It came just a day after he said "a decision has been made" for up to 50,000 North Korean troops to be sent to fight for Russia."Everyone around the world must understand what this means," Mr Zelenskyy said in a post on social media.Ukrainian President Volodymyr Zelenskyy has said up to 50,000 North Korean soldiers will be deployed to fight for Russia. (Reuters: Marko Djurica)In late 2024, North Korea sent an estimated 14,000 soldiers to fight for Russia.But if Mr Zelenskyy is correct, more troops may be on the way in what would represent a major escalation in North Korea's involvement in the war in Ukraine.What happened to the Ukrainian family?Last week mourners gathered in the village of Radushne in Ukraine's Dnipropetrovsk region to farewell the Voronov family, who were killed in the Russian attack at the end of July.Five coffins were carried into the church – for the father, mother and three of their children. Soft toys were placed on two of the lids.Mr Zelenskyy shared a photo of the family in a post on X on July 30, and wrote the Russian missile strike was so powerful that "almost nothing remained of the family's house."This was the Voronov family: mom Olena, dad Artem, seven children — Mark, Dominika, Zakhar, Azariah Ilay, Federica, Emilia, Viorika — and their one-and-a-half-year-old grandson Artem, the child of their eldest son, who is currently defending Ukraine," Mr Zelenskyy wrote.The fate of the five of other family members, including Artem, who were in the house at the time of the strike, remained unknown, he said.At the funeral, Artem's mother, Iryna Bolhar, told Reuters news agency: "I got a phone call and was simply told that he was no longer with us.""We still held out hope that they would find him wounded, but they had already said for certain that he was gone."Is North Korea sending soldiers, supplies to Russia?Ukraine's military intelligence agency has said a specialist missile unit from North Korea had begun deploying to Russia.It said the unit could be equipped with up to 120 ballistic missiles, six launchers and 90 personnel.North Korean leader Kim Jong Un shares a laugh with soldiers during a visit to a base in November. (Supplied: KCNA via Reuters)Anton Sokolin from Korea Risk Group said videos were circulating online in Russia and Ukraine "purporting to show" those North Korean soldiers.He added there was speculation more details about the missile unit may be revealed next month during some sort of engagement between the two leaders, but confirmed detail is scant.Mr Zelenskyy said in July that Russia had requested 30,000 additional troops from North Korea, in a later social media post he said it is "30,000 to 50,000".He paired the information about the potential troop deployment with a call for South Korea to provide support for Ukraine's air defences.The potential deployment is yet to be confirmed by a secondary source, like South Korea's National Intelligence Service."The movement of soldiers is not that difficult to observe," Dr Go Myong-Hyun from the Institute for National Security Strategy told the ABC."North Korea is under surveillance pretty much 24/7, that is the combined surveillance of America and South Korea."He said that does not mean the deployment is not happening — it could be in early preparation stages — but he warns it should be treated with "caution" until there is confirmation, given it represents such a significant escalation.Mr Sokolin was similarly circumspect. He said as the information had come from a "credible source like Zelenskyy" it should be treated as "legitimate", but it was necessary to watch for actual signs of the deployment."It is really hard to rule it out completely, at the same time I do believe we have to treat this information with a grain of salt."What are the ties between Russia and Ukraine?Russia and North Korea have been significantly deepening their ties in recent years.The Ukrainian leader has said Pyongyang is supplying weapons to Russia, with Kyiv finding some North Korean missiles in Ukraine's territory.In May last year North Korea's leader, Kim Jong-Un, justified sending soldiers to Russia as being part of the defence of a "brother nation".North Korea and Russia signed a treaty, which included security assistance obligations, when Vladamir Putin visited Pyongyang in 2024.Russian President Vladimir Putin turned to North Korea when he needed soldiers to bolster his invasion of Ukraine. (Pool: Alexander Nemenov via Reuters)Work on the first road bridge to connect the countries is also nearing completion.The bridge across the Tumen River will allow for easier transport of goods — including military equipment, to pass between them and will make it more difficult to surveil."If that link is fully functional there will be even more exchanges and something that is very hard to track, because there will just be trucks going in and out of the country — you can put pretty much any exchange on the table, it all could be hidden," Mr Sokolin said.What does North Korea get out of it?Analysts say North Korea would be rewarded for sending more soldiers to fight in Ukraine, with economic support and access to military technology.Ukraine's military intelligence agency has said a specialist missile unit from North Korea had begun deploying to Russia.