Bosnia has a significant Serbian population. abkhazia, transnisia, luhansk etc. always the same scenario; incite the minorities there; They are committing genocide so that it is an excuse to attack.
Now there is the threat that if you become a member of NATO, I will vote. If Putin can start another war in the middle of Europe, he will be very happy. He will do his best to provoke the nationalist Serbs.
If it succeeds in provoking the Serbs, Bosnia (if it does not become a NATO member) will be subject to intervention to protect the Serb minority. if he intends to become a member because he intends to become a member...
Independent of this, the EU is expected to accept Serbia as a member in 3-4 years. (target 2025). Losing such an ally is what really bothers the Russians. because being accepted into eu means accepting eu norms; means promoting to those standards in education and human rights.
If Putin forces it, it will start a civil war in Serbia.
even Bulgaria has reached a new age with its EU membership; he still has a long way to go, but I can't imagine how the Bulgarians, whom we get angry with from time to time, would be without EU membership. Even Bulgaria has been a NATO member for 15 years, while Russia drinks a glass of water for Bosnia.