My travel guide has an article about Khasan: https://en.wikivoyage.org/wiki/Khasan
The article makes it look like a potentially interesting travel destination, with a picture of the monument dedicated to the historic Battle of Lake Khasan that happened there, and a mention of its unique geographical position:
The article does not contain any particular warning, just mentioning the train line in the "Get in" section.
Question: Is it really a place where tourists can go, for instance from Vladivostok?
I am sure the place is interesting in itself due to its uniqueness and battle history, but do they allow casual tourists to even enter the town? Is it just like another other minor Russian town, or on the opposite is it a kind of prohibited or permit-only zone?