Vladivostok is not that far from the border with North Korea, and it is both populated and industrialized, as well as having port access. Vladivostok is a strategic city. During the Cold War, it was a first-class target.
Still less critical than the Chinese areas and it will only able to take a relatively small group of refugees. Compare this temporary expansion of the population with the benefit of an America collapsed in on itself in a civil war. Now fat boy wants to nuke Guam. He is fixated on us.