I'm 100% sure that there was a purpose behind posting or releasing such a video," Konrad Muzyka, an aerospace and defense consultant focused on Russia and Belarus, told CBS News."This video of a train is a very good example of Russian strategy of trying to increase the pressure on the West and signal its — maybe not necessarily readiness — but willingness to escalate the situation," Muzyka said.There were also reports in the British press, which Muzyka said were incorrect, that the train featured in the online video was heading toward Russia's border with Ukraine."Going forward, we are going to see more reports about Russian activities that relate to nuclear weapons, that relate to drills of units which can potentially be carrying nuclear warheads," Muzyka said.Ukraine's President Volodymyr Zelenskyy appeared to take the threat seriously, telling CBS' "Face the Nation" on Sunday: "Maybe yesterday it was a bluff."