>

3) sign it, then claim Ukraine broke it thus giving them an excuse to join the Russian effort further.
This agreement isn't worth anything with Lukashenko and Putin still in play.
Aren’t we a little bit past that point now? >

IF a request like this was signed it would likely be for 1 of 2 reasons
1: Stop Russia from being strengthed during the coming rumored offensive
2: Give Belarus a final chance to reintegrate into the larger European sphere, as assisting Russia with its troops in Ukraine would be the final death knell. Belarus as a country would simply cease to exist as far as the European Markets and Governments would see it.
Edit: I do am have stupid. Knell*