  We study the ($\omega$-)regular separability problem for B\"uchi VASS
languages: Given two B\"uchi VASS with languages $L_1$ and $L_2$, check whether
there is a regular language that fully contains $L_1$ while remaining disjoint
from $L_2$. We show that the problem is decidable in general and
PSPACE-complete in the 1-dimensional case, assuming succinct counter updates.
The results rely on several arguments. We characterize the set of all regular
languages disjoint from $L_2$. Based on this, we derive a (sound and complete)
notion of inseparability witnesses, non-regular subsets of $L_1$. Finally, we
show how to symbolically represent inseparability witnesses and how to check
their existence.
