The problem is not that the Belarusian regime got involved in a war of aggression. The problem is that it got involved in a war that was always impossible to win.
At the time of writing (2022-02-26 14:28 UTC+3), the armed forces of Ukraine are maintaining combat effectiveness, control all major cities, and are inflicting heavy damage on invading Russian troops. Russia appears to have assumed that mass panic and spontaneous disintegration of the Ukrainian military-political administration would render a decapitation strike unnecessary and that the West would remain passive. This indicates weak situational analysis based on wishful thinking rather than facts.
The Republic of Belarus is recognised by the world community as an accomplice in this aggression against Ukraine. Sanctions have been imposed against several Belarusian individuals and entities, including the largest export-oriented enterprises. This is only the beginning: Belarus will suffer the double blow of direct sanctions against itself and collateral adverse effects from sanctions against Russia. At the highest level, the Belarusian regime made no attempt to disassociate itself from the use of Belarusian territory by Russian invasion forces for aggression against Ukraine.
Rumours circulate about the possible direct involvement of the Belarusian army in operations against Ukraine in the coming days; however, there is no confirmation of this at the time of writing.
The successful resistance of Ukraine and the prompt response of the West came as a complete surprise to Minsk. A “small victorious war” will not work; the scale of the costs of participating in this adventure are impossible to predict. Separate negotiations with the West and Ukraine are the best option remaining to the Belarusian regime, but time is running out. After the Kremlin begins negotiations with Kyiv, no one will talk to Minsk.