Could you please define annexing here? Technically Russia and Belarus are already a Union: https://en.m.wikipedia.org/wiki/Union_State

I think any kind of tighter integration is going to happen via this entity. Lukashenko signed a bunch of documents for further integration, although he keeps intentionally flaking on them.

@42irrationalist By annexing I meant with military force or other pressure not via the ongoing process of integration. Both would resolve as a yes.